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Samacheer Kalvi 12th Economics Solutions Chapter 3 Theories of Employment and Income

April 24, 2024

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Samacheer Kalvi 12th Economics Theories of Employment and Income Text Book Back Questions and Answers

Part – A
Multiple Choice Questions.

Question 1.
Every able bodied person who is willing to work at the prevailing wage rate is employed called as –
(a) Full employment
(b) Under employment
(c) Unemployment
(d) Employment opportunity
Answer:
(a) Full employment

Question 2.
Structural unemployment is a feature in a –
(a) Static society
(b) Socialist society
(c) Dynamic society
(d) Mixed economy
Answer:
(c) Dynamic society

Question 3.
In disguised unemployment, the marginal productivity of labour is –
(a) Zero
(b) One
(c) Two
(d) Positive
Answer:
(a) Zero

Question 4.
The main concention of the Classical Economic Theory is –
(a) Under employment
(b) Economy is always in the state of equilibrium
(c) Demand creates its supply
(d) Imperfect competition
Answer:
(b) Economy is always in the state of equilibrium

Question 5.
J.B. Say is a –
(a) Neo Classical Economist
(b) Classical Economist
(c) Modem Economist
(d) New Economist
Answer:
(b) Classical Economist

Question 6.
According to Keynes, which type of unemployment prevails in capitalist economy?
(a) Full employment
(b) Voluntary unemployment
(c) Involuntary unemployment
(d) Under employment
Answer:
(d) Under employment

Question 7.
The core of the classical theory of employment is –
(a) Law of Diminishing Return
(b) Law of Demand
(c) Law of Markets
(d) Law of Consumption
Answer:
(c) Law of Markets

Question 8.
Keynes attributes unemployment to –
(a) A lack of effective supply
(b) A lock of effective demand
(c) Alack of both
(d) None of the above
Answer:
(b) A lock of effective demand

Question 9.
…………………… Flexibility brings equality between saving and investment.
(a) Demand
(b) Supply
(c) Capital
(d) Interest
Answer:
(d) Interest

Question 10.
……………………. theory is a turning point in the development of modem economic theory.
(a) Keynes’
(b) Say’s
(c) Classical
(d) Employment.
Answer:
(a) Keynes’

Question 11.
The basic concept used in Keynes Theory of Employment and Income is –
(a) Aggregate demand
(b) Aggregate supply
(c) Effective demand
(d) Marginal Propensity Consume
Answer:
(c) Effective demand

Question 12.
The component of aggregate demand is –
(a) Personal demand
(b) Government expenditure
(c) Only export
(d) Omli import
Answer:
(b) Government expenditure

Question 13.
Aggregate supply is equal to –
(a) C +1 + G
(b) C + S + G + (x – m)
(c) C + S + T + (x-m)
(d) C + S + T + Rf
Answer:
(d) C + S + T + Rf

Question 14.
Keynes theory pursues to replace laissez faire by –
(a) No government intervention
(b) Maximum intervention
(c) State intervention in certain situation
(d) Private sector intervention
Answer:
(c) State intervention in certain situation

Question 15.
In Keynes theory of employment and income, ……………………… is the basic cause of economic depression.
(a) Less production
(b) More demand
(c) Inelastic supply
(d) Less aggregate demand in relation to productive capacity.
Answer:
(d) Less aggregate demand in relation to productive capacity.

Question 16.
Classical theory advocates –
(a) Balanced budget
(b) Unbalanced budget
(c) Surplus budget
(d) Deficit budget
Answer:
(a) Balanced budget

Question 17.
Keynes theory emphasized on ……………………….. equilibrium.
(a) Very short run
(b) Short run
(c) Very long run
(d) Long run
Answer:
(b) Short run

Question 18.
According to classical theory, rate of interest is a reward for –
(a) Investment
(b) Demand
(c) Capital
(d) Saving
Answer:
(d) Saving

Question 19.
In Keynes theory, the demand for and supply of money are determined by –
(a) Rate of interest
(b) Effective demand
(c) Aggregate demand
(d) Aggregate supply
Answer:
(a) Rate of interest

Question 20.
Say’s law stressed the operation of ……………………… in the economy.
(a) Induced price mechanism
(b) Automatic price mechanism
(c) Induced demand
(d) Induced investment
Answer:
(b) Automatic price mechanism

Part – B
Answer The Following Questions In One or Two Sentences.

Question 21.
Define full employment?
Answer:
Full employment refers to a situation in which every able bodied person who is willing to work at the prevailing wage rate, is employed. In other words full employment means that persons who are willing to work and able to work must have employment or a job.

Question 22.
What is the main feature of rural unemployment?
Answer:

India’s rural economy has both unemployment and underemployment.
The major feature of rural unemployment is the existence of unemployment in the form of disguised unemployment and seasonal unemployment.
In agriculture and agro based industries like sugar, production activities are carried out only in some seasons.

Question 23.
Give short note on frictional unemployment?
Answer:
Frictional Unemployment (Temporary Unemployment):

Frictional unemployment arises due to imbalance between supply of labour and demand for labour.
This is because of immobility of labour, lack of necessary skills, break down of machinery, shortage of raw materials etc.
The persons who lose jobs and in search of jobs are also included under frictional unemployment.

Question 24.
Give reasons for labour retrenchment at present situation?
Answer:

Modem technology being capital intensive requires less labourers and contributes to ’ technological unemployment.
Now a days, invention and innovations lead to the adoption of new techniques there by the existing workers are retrenched.
Labour saving devices are responsible for technological unemployment.

Question 25.
List out the assumptions of Say’s law?
Answer:
The Say’s Law of market is based on the following assumptions:

No single buyer or seller of commodity or an input can affect price.
Full employment.
People are motivated by self interest and self – interest determines economic decisions.
The laissez faire policy is essential for an automatic and self adjusting process of full employment equilibrium. Market forces determine everything right.
There will be a perfect competition in labour and product market.
There is wage-price flexibility.
Money acts only as a medium of exchange.
Long – run analysis.
There is no possibility for over production or unemployment.

Question 26.
What is effective demand?
Answer:

The starting point of Keynes theory of employment and income is the principle of effective demand.
Effective demand denotes money actually spent by the people on products of industry.
The money which entrepreneurs receive is paid in the form of rent, wages, interest and profit.
Therefore effective demand equals national income.

Question 27.
What are the components of aggregate supply?
Answer:
Aggregate demand has the following four components:

Consumption demand
Investment demand
Government expenditure and
Net Export (export – import)

Part – C
Answer The Following Questions In A Paragraph.

Question 28.
Explain the following in short:

Seasonal unemployment
Frictional unemployment
Educated unemployment

Answer:
Seasonal Unemployment:

This type of unemployment occurs during certain seasons of the year.
In agriculture and agro based industries like sugar,production activities are carried out only in some seasons.
These industries offer employment only during that season in a year. Therefore people may remain unemployed during the off season.
Seasonal unemployment happens from demand side also; for example ice cream industry, holiday resorts etc.

Frictional Unemployment (Temporary Unemployment):

Frictional unemployment arises due to imbalance between supply of labour and demand for labour.
This is because of immobility of labour, lack of necessary skills, break down of machinery, shortage of raw materials etc.
The persons who lose jobs and in search of jobs are also included under frictional unemployment.

Educated Unemployment:

Sometimes educated people are underemployed or unemployed when qualification does not match the job.
Faulty education system, lack of employable skills, mass student turnout and preference for white collar jobs are highly responsible for educated unemployment in India.

Question 29.
According to classical theory of employment, how wage reduction solves the problem of unemployment? Diagrammatically explain?
Answer:
The classical theory of employment assumes that the economy operates at the level of full employment without inflation in the long period. It also assumes that wages and prices of goods are flexible and the competitive market exists in the economy (laissez – faire economy). According to the classical theory of employment, full employment condition can be achieved by cutting down the wage rate. Unemployment would be eliminated when wages are determined by the mechanism of economy itself. The following figure shows the relationship between wage rate and employment:
Samacheer Kalvi 12th Economics Chapter 3 Theories of Employment and Income
In the figure, when the wage rate is OW, then the employment is ON. As the wage rate is reduced to OW¹, then the employment has increased to ON¹. Prof. Pigou has taken this theory as base for developing the solution of unemployment problem.

Question 30.
Write short note on the implications of Say’s law?
Answer:
Implications of Say’s Law:

There is no possibility for over production or unemployment.
If there exist unutilized resources in the economy, it is profitable to employ them up to the point of full employment. This is true under the condition that factors are willing to accept rewards on a par with their productivity.
As automatic price mechanism operates in the economy, there is no need for government intervention. (However, J.M. Keynes emphasized the role of the State)
Interest flexibility brings about equality between saving and investment.
Money performs only the medium of exchange function in the economy, as people will not hold idle money.

Question 31.
Explain Keynes’ theory in the form of flow chart?
Answer:
Samacheer Kalvi 12th Economics Chapter 3 Solutions Theories of Employment and Income

Question 32.
What do you mean by aggregate demand? Mention its components?
Answer:

The aggregate demand is the amount of money which entrepreneurs expect to get by selling the output produced by the number of labourers employed.
Therefore, it is the expected income or revenue from the sale of output at different levels of employment.
Aggregate demand has the following four components:
1. Consumption demand
2. InvestmenTdemand
3. Government expenditure and
4. Net Export (export – import)

Question 33.
Explain about aggregate supply with the help of diagram?
Answer:

Aggregate supply function is an increasing function of the level of employment.
Aggregate supply refers to the value of total output of goods and services produced in an economy in a year.
In other words, aggregate supply is equal to the value of national product, i.e., national income.
Aggregate Supply = C + S + T + Rf = Aggregate income generated in the economy.
The following figure shows the shape of the two aggregate supply curves drawn for the assumption of fixed money wages and variable wages.

Aggregate Supply Curve

Z curve is linear where money wages remains fixed; Z<sub>1</sub> curve is non – linear since wage rate increases with employment.
When full employment level of Nf is reached it is impossible to increase output by employing more men.
So aggregate supply curve becomes inelastic (Vertical straight line).
The slope of the aggregate supply curve depends on the relation between the employment and productivity.
Based upon this relation, the aggregate supply curve can be expected to slope upwards.
In reality the aggregate supply curve will be like Z₁
Therefore, the aggregate supply depends on the relationship between price and wages.

Samacheer Kalvi 12th Economics Chapter 3 Solutions Theories of Employment and Income

Question 34.
Write any five differences between classism and Keynesianism?
Answer:
Comparison of Classicism and Keynesianism
Keynesianism:

Short – run equilibrium Saving is a vice
The function of money is a medium of exchange on the one side and a store of value on the other side.
Macro approach to national problems
State intervention is advocated

Classicism:

Long – run equilibrium
Saving is a social virtue
The function of money is to act as a medium of exchange.
Micro foundation to macro problems
Champions of Laissez – fair policy

Part – D
Answer The Following Questions In One Page.

Question 35.
Describe the types of unemployment?
Answer:
The following are the types of unemployment.
Types of unemployment:

Cyclical Unemployment
Frictional Unemployment
Technical Unemployment
Disguised Unemployment
Seasonal Unemployment
Educated Unemployment
Structural Unemployment

1. Cyclical Unemployment:

This unemployment exists during the downturn phase of trade cycle in the economy.
In a business cycle during the period of recession and depression, income and output fall leading to widespread unemployment.
It is caused by deficiency of effective demand.
Cyclical unemployment can be cured by public investment or expansionary monetary policy.

2. Seasonal Unemployment:

This type of unemployment occurs during certain seasons of the year.
In agriculture and agro based industries like sugar, production activities are carried out only in some seasons.
These industries offer employment only during that season in a year. Therefore people may remain unemployed during the off season.
Seasonal unemployment happens from demand side also; for example ice cream industry, holiday resorts etc.

3. Frictional Unemployment (Temporary Unemployment):

Frictional unemployment arises due to imbalance between supply of labour and demand for labour.
This is because of immobility of labour, lack of necessary skills, break down of machinery, shortage of raw materials etc.
The persons who lose jobs and in search of jobs are also included under frictional unemployment.

4. Educated Unemployment:

Sometimes educated people are underemployed or unemployed when qualification does not match the job.
Faulty education system, lack of employable skills, mass student turnout and preference for white collar jobs are highly responsible for educated unemployment in India.

5. Technical Unemployment:

Modem technology being capital intensive requires less labourers and contributes to technological unemployment.
Now a days, invention and innovations lead to the adoption of new techniques there by the existing workers are retrenched.
Labour saving devices are responsible for technological unemployment.

6. Structural Unemployment:

Structural unemployment is due to drastic change in the structure of the society.
Lack of demand for the product or shift in demand to other products cause this type of unemployment.
For example rise in demand for mobile phones has adversely affected the demand for cameras, tape recorders etc.
So this kind of unemployment results from massive and deep rooted changes in economic structure.

7. Disguised Unemployment:

Disguised unemployment occurs when more people are than what is actually required.
Even if some workers are withdrawn, production does not suffer.
This type of unemployment is found in agriculture.
A person is said to be disguisedly by unemployed if his contribution to output is less than what he can produce by working for normal hours per day.
In this situation, marginal productivity of labour is zero or less or negative.

Question 36.
Critically explain Say’s law of market?
Answer:
Criticisms of Say’s Law:
The following are the criticisms against Say’s law:

According to Keynes, supply does not create its demand. It is not applicable where demand does not increase as much as production increases.
Automatic adjustment process will not remove unemployment. Unemployment can be removed by increase in the rate of investment.
Money is not neutral. Individuals hold money for unforeseen contingencies while businessmen keep cash reserve for future activities.
Say’s law is based on the proposition that supply creates its own demand and there is no over production. Keynes said that over production is possible.
Keynes regards full employment as a special case because there is under – employment in capitalist economies.
The need for state intervention arises in the case of general over production and mass unemployment.

Question 37.
Narrate the equilibrium between ADF and ASF with diagram? Equilibrium between ADF and ASF?
Answer:

Under the Keynes theory of employment, a simple two sector economy consisting of the household sector and the business sector is taken to understand the equilibrium between ADF and ASF.
All the decisions concerning consumption expenditure are taken by the individual households, while the business firms take decisions concerning investment.
It is also assumed that consumption function is linear and planned investment is autonomous.
There are two approaches to determination of the equilibrium level of income in Keynesian theory. These are:
1. Aggregate demand – Aggregate supply approach
2. Saving – Investment approach –
In this chapter, out of these two, aggregate demand and aggregate supply approach is alone explained to understand the determination of equilibrium level of income and employment.
The concept of effective demand is more clearly shown in the figure.
In the figure, the aggregate demand and aggregate supply reach equilibrium at point E. The employment level is N0 at that point.
At ON₁ employment, the aggregate supply is N, Rr But they are able to produce M₁ N₁ The expected level of profit is M₁, R₁
To attain this level of profit, entrepreneurs will employ more labourers.
The tendency to employ more labour will stop once they reach point E.
At all levels of employment beyond, ON₀, the aggregate demand curve is below the aggregate supply curve indicating loss to the producers.
Hence they will never employ more than ON₀ labour.
Thus effective demand concept becomes a crucial point in determining the equilibrium level of output in the capitalist economy or a free market economy in the Keynesian system.
It is important to note that the equilibrium level of employment need not be the full employment level (N<sub>1</sub>) from the Figure, it is understood that the difference between N₀ – N₀ is the level of unemployment.
Thus the concept of effective demand becomes significant in explaining the under employment equilibrium.

Samacheer Kalvi 12th Economics Chapter 3 Solutions Theories of Employment and Income

Question 38.
Explain the differences between classical theory and Keynes theory?
Answer:
Keynesianism:

Short – run equilibrium
Saving is a vice
The function of money is a medium of exchange on the one side and a store of value on the other side.
Macro approach to national problems
State intervention is advocated.
Applicable to all situations – full employment and less than full employment.
Capitalism has inherent contradictions
Budgeting should be adjusted to the requirements of economy.
The equality between saving and investment is advanced through changes in income.
Rate of interest is determined by the demand for and supply of money.
Rate of interest is a flow.
Demand creates its own supply.
Rate of interest is a reward for parting with liquidity.

Classicism:

Long – run equilibrium
Saving is a social virtue.
The function of money is to act as a medium of exchange
Micro foundation to macro problems
Champions of Laissez – fair policy
Applicable only to the full employment situation.
Capitalism is well and good.
Balanced budget
The equality between saving and investment is achieved through changes of rate of interest.
Rate of interest is determined by saving and investment.
Rate of interest is a stock.
Supply creates its own demand.
Rate of interest is a reward for saving.

Samacheer Kalvi 12th Economics Theories of Employment and Income Addtional Questions and Answers

Part – A
I. Multiple Choice Questions.

Question 1.
Who is one of the greatest and most influential economist?
(a) J.M. Keynes
(b) Adam Smith
(c) Marshall
(d) Simon Kuznets
Answer:
(a) J.M. Keynes

Question 2.
Keynes book “The General theory of Employment, Interest and Money” published in –
(a) 1926
(b) 1936
(c) 1946
(d) 1956
Answer:
(b) 1936

Question 3.
The total stock of money circulating in an Economy is called –
(a) Money
(b) Capital
(c) Money Supply
(d) Finance
Answer:
(c) Money Supply

Question 4.
The …………………… function depends upon Income of the people and marginal propensity to consume?
(a) demand
(b) consumption
(c) supply
(d) marginal
Answer:
(b) consumption

Question 5.
Every economy in the world aims at attaining the level of –
(a) full employment
(b) under employment
(c) un employment
(d) employment opportunity
Answer:
(a) full employment

Question 6.
…………………… is an increasing function of the level of employment –
(a) Aggregate supply function
(b) Aggregate demand function
(c) Aggregate consumption function
(d) Aggregate consumption expenditure
Answer:
(a) Aggregate supply function

Question 7.
Effective demand signifies the money spent on consumption of goods and services and on –
(a) capital
(b) investment
(c) profit
(d) finance
Answer:
(b) investment

Question 8.
Who has given importance to the concept of liquidity preference?
(a) Kuznet
(b) Marshall
(c) Keynes
(d) Adam Smith
Answer:
(c) Keynes

Question 9.
…………………….. was a French Economist and an Industrialist?
(a) J.B. Say
(b) Keynes
(c) Adam Smith
(d) David Ricardo
Answer:
(a) J.B. Say

Question 10.
Frictional unemployment another name is called –
(a) Educated unemployment
(b) Seasonal unemployment
(c) Temporary unemployment
(d) Technical unemployment
Answer:
(c) Temporary unemployment

Question 11.
Discussed unemployment is mostly found in –
(a) agriculture
(b) sericulture
(c) industry
(d) architecture
Answer:
(a) agriculture

Question 12.
The main reason for massive unemployment is poor –
(a) economic planning
(b) educational planning
(c) military planning
(d) man power planning
Answer:
(d) man power planning

Question 13.
The Employment Assurance Scheme was launched in the year –
(a) 1983
(b) 1993
(c) 2003
(d) 2013
Answer:
(b) 1993

Question 14.
Cyclical unemployment is caused by …………………………. cycles.
(a) business
(b) money
(c) trade
(d) finance
Answer:
(c) trade

Question 15.
The problem of rural unemployment can be solved only by ………………………….. agriculture.
(a) modernising
(b) agro based
(c) innovative
(d) new method followed
Answer:
(a) modernising

Question 16.
Unemployment is classified as voluntary unemployment and –
(a) involuntary unemployment
(b) cyclical unemployment
(c) rural unemployment
(d) seasonal unemployment
Answer:
(b) cyclical unemployment

Question 17.
Existence of Joint Family System in India promotes –
(a) educational unemployment
(b) disguised unemployment
(c) seasonal unemployment
(d) voluntary unemployment
Answer:
(b) disguised unemployment

Question 18.
Educated and skilled persons who may not accept casual work. This is called ………………………. unemployment.
(a) closed
(b) open
(c) seasonal
(d) disguised unemployment
Answer:
(b) open

Question 19.
………………………. law of market was the basis for assuming the situation of full employment.
(a) J.B. Say
(b) Keynes
(c) Marshall
(d) Lemer
Answer:
(a) J.B. Say

Question 20.
The aggregate effective demand would increase the level of –
(a) unemployment
(b) employment
(c) cyclical unemployment
(d) open unemployment
Answer:
(b) employment

Question 21.
…………………. refers to the labour force of a country.
(a) Employment
(b) Unemployment
(c) Full employment
(d) Open employment
Answer:
(c) Full employment

Question 22.
…………………. means that persons who are willing to work and able to work must have employment or a job?
(a) Full employment
(b) Unemployment
(c) Educational unemployment
(d) Seasonal unemployment
Answer:
(a) Full employment

Question 23.
………………….. is the principle of effective demand?
(a) Profit
(b) Income
(c) Money
(d) Interest
Answer:
(a) Profit

Question 24.
When goods are produced by firms in the economy, they pay reward to the factors of the production is called –
(a) J.M. Keynes
(b) Adam Smith
(c) J.B. Say
(d) Ricardo
Answer:
(c) J.B. Say

Question 25.
…………………….. defines “Full employment as that level of employment at which any further increase in spending would resort in an inflationary spiral of wages and prices”
(a) Lemer
(b) J.M. Keynes
(c) J.B. Say
(d) Adam Smith
Answer:
(a) Lemer

II. Match the following and choose the correct answer by using codes given below

Question 1.
A. Full employment – (i) Qualified job
B. Educated unemployment – (ii) Deficiency of effective demand
C. Cyclical unemployment – (iii) During season of the year
D. Seasonal unemployment – (iv) Learner
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (ii) B (iv) C (i) D (iii)
(c) A (iv) B (i) C (ii) D (iii)
(d) A (iii) B (iv) C (i) D (ii)
Answer:
(c) A (iv) B (i) C (ii) D (iii)

Question 2.
A. Public Investment – (i) Temporary unemployment
B. Production activities only in Some seasons – (ii) Deficiency of effective demand
C. Frictional unemployment – (iii) During season of the year
D. Educated unemployment – (iv) Learner
Codes:
(a) A (ii) B (ii) C (iii) D (iv)
(b) A (iii) B (ii) C (iv) D (i)
(c) A (i) B (iii) C (ii) D (iv)
(d) A (iv) B (i) C (iii) D (ii)
Answer:
(a) A (ii) B (ii) C (iii) D (iv)

Question 3.
A. ED – (i) Income of the people
B. ADF – (ii) Y = C + I = Output = Employment
C. ASF – (iii) C + I + G + (X – M)
D. CF – (iv) C + S + T + Rf = Aggregate Income generated in the economy
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (iii) B (i) C (iv) D (i)
(c) A (iv) B (ii) C (i) D (iii)
(d) A (iv) B (iii) C (iv) D (i)
Answer:
(d) A (iv) B (iii) C (iv) D (i)

Question 4.
A. Keynes concept – (i) Aggregate spending
B. Demand – (ii) Liquidity preference
C. Aggregate supply – (iii) To spend on domestic output
D. Aggregate demand – (iv) The value of national product
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (ii) B (i) C (iv) D (iii)
(c) A (iii) B (iv) C (ii) D (i)
(d) A (iv) B (iii) C (i) D (ii)
Answer:
(b) A (ii) B (i) C (iv) D (iii)

Question 5.
A. Keynesianism – (i) Long run – equilibrium
B. Classicism – (ii) Short run – equilibrium
C. Keynesianism – (iii) State intervention is advocated
D. Classicism – (iv) Saving is a vice
Codes:
(a) A (ii) B (i) C (iv) D (iii)
(b) A (i) B (ii) C (iii) D (iv)
(c) A (iii) B (iv) C (ii) D(i)
(d) A (iv) B (iii) C (i) D (ii)
Answer:
(a) A (ii) B (i) C (iv) D (iii)

III. State whether the statements are true or false

Question 1.
(i) The function of money is a medium of exchange on the one side and a store of value on the other side is called Keynesianism.
(ii) Macro approach to national problems.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 2.
(i) Aggregate demand has the four components are consumption demand, investment demand, Government expenditure and Net export.
(ii) Aggregate demand refers to the required amount of labourers and materials to produce the neccessary output.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(c) (i) is true but (ii) is false

Question 3.
(i) Keynesian theory is – Aggregate demand – Aggregate supply approach. Saving – Investment approach.
(ii) This approach explained the determination level of Income and employment.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 4.
(i) Effective demand denotes money actually spent by the people on products of Industry and agriculture.
(ii) Effective demand equals to State Income.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(b) Both (i) and (ii) are false

Question 5.
(i) “Supply creates its own Demand”.
(ii) The aggregate demand and aggregate supply reach equilibrium at point ‘E’.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

IV. Which of the following is correctly matched

Question 1.
(a) Seasonal unemployment – Type of unemployment
(b) Technical unemployment – Some season only
(c) Cyclical unemployment – Public capital
(d) Full employment – Not willing to job
Answer:
(a) Seasonal unemployment – Type of unemployment

Question 2.
(a) Frictional unemployment – Permanant
(b) Educated unemployment – White collar jobs
(c) Structural unemployment – In search job
(d) Disguised unemployment – Found in industry
Answer:
(b) Educated unemployment – White collar jobs

Question 3.
(a) Keynes – A general theory
(b) Aggregate supply – A level of money
(c) Keynesianism – Champions of Laissez – Faire
(d) Effective demand – Classical Economy
Answer:
(a) Keynes – A general theory

Question 4.
(a) Effective demand – Income Effective
(b) Aggregate demand – Money demand
(c) Say’s law – Supply creates own demand
(d) Aggregate supply – Money supply
Answer:
(c) Say’s law – Supply creates own demand

Question 5.
(a) J.B. Say – Industrialist
(b) Adam Smith – Classical Economist
(c) David Ricardo – Capitalist Economist
(d) Lemer – Socialist
Answer:
(a) J.B. Say – Industrialist

V. Which of the following is not correctly matched

Question 1.
(a) Say’s law of Market – Classical theory of Employment
(b) Adam Smith – Wealth of nations
(c) Keynes – The General theory of Employment, Interest and Money
(d) A.C. Pigou – French Economist
Answer:
(d) A.C. Pigou – French Economist

Question 2.
(a) Full Employment – Willing to work and able to work
(b) Unemployment – Cannot find suitable job
(c) Underemployment – Not fully utilized
(d) Disguised unemployment – More people not working
Answer:
(d) Disguised unemployment – More people not working

Question 3.
(a) Keynes – Liquidity preference
(b) Aggregate demand – Consumption demand
(c) Consumption function – Money supply
(d) Marginal effeciency of capital – Investment level
Answer:
(c) Consumption function – Money supply

Question 4.
(a) Effective demand – Y = C + I = Output = Employment
(b) Aggregate supply – C + S + T + Rf = Aggregate Income
(c) Aggregate demand – C + I + G + (X – M)
(d) Aggregate private saving – C + S + T
Answer:
(d) Aggregate private saving – C + S + T

Question 5.
(a) Keynesianism – Capitalism has inherant contradictions
(b) Classism – Capitalism well and good
(c) Keynesian theory – Saving – Investment approach
(d) Frictional – Full employment
Answer:
(d) Frictional – Full employment

VI. Pick the odd one out

Question 1.
Types of unemployment
(a) Cyclical unemployment
(b) Seasonal unemployment
(c) Frictional unemployment
(d) nature unemployment
Answer:
(d) nature unemployment

Question 2.
Classical theory was developed by –
(a) David Ricardo
(b) Adam Smith
(c) J.S. Mill
(d) J.B. Say
Answer:
(b) Adam Smith

Question 3.
The Say’s law of Market Assumptions are –
(a) No single buyer
(b) Full employment
(c) Money is not neutral
(d) Wage flexibility
Answer:
(c) Money is not neutral

Question 4.
Keynesianism is called –
(a) Short run equilibrium
(b) saving is social virtue
(c) Macro approach to national problems
(d) State intervention is advocated
Answer:
(b) Saving is social virtue

Question 5.
Classicism is called –
(a) Capatalism is well and good
(b) Balanced Budget
(c) savinf is vice
(d) Micro foundation to Macro problems
Answer:
(c) Saving is vice

VII. Assertion and Reason

Question 1.
Assertion (A): Modem technology being capital intensive requires less labourers, and contributes to technological unemployment.
Reason (R): Now – a – days invention and innovations lead to the adoption of new techniques there by the existing workers are retrenched.

(a) Both ‘A’ and ‘R’ are tme and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are tme but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is tme but ‘R’ is false
(d) ‘A’ is false but ‘R’ is tme .
Answer:
(a) Both ‘A’ and ‘R’ are tme and ‘R’ is the correct explanation to ‘A’

Question 2.
Assertion (A): According to say, “when goods are produced by firms in the Economy”.
Reason (R): There was no single theory which could be labeled as classical theory of employment.

(a) Both ‘A’ and ‘R’ are tme and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(c) ‘A’ is true but ‘R’ is false

Question 3.
Assertion (A): Keynes book “The General theory of Employment, Interest and Money” published in 1916.
Reason (R): A turning point in the development of modem economic theory – Keynes.

(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(d) ‘A’ is false but ‘R’ is true

Question 4.
Assertion (A): Aggregate supply function is increasing function of the level of employment.
Reason (R): Aggregate supply is only state product.

Question 5.
Assertion (A): Keynesianism is Macro approach to national problems.
Reason (R): Keynesianism is state intervention is advocated.

(a) Both ‘A’ and ‘R’ are tme and ‘R’ is the correct explanation to ‘A’
(.b) Both ‘A’ and ‘R’ are tme but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is tme but ‘R’ is false
(d) ‘A’ is false but ‘R’ is tme
Answer:
(d) ‘A’ is false but ‘R’ is tme

Part – B
Answer The Following Questions In One or Two Sentences

Question 1.
Write two approaches of the equilibrium level of Income in Keynesian theory?
Answer:
There are two approaches te determination of the equilibrium level of income in Keynesian theory. These are:

Aggregate demand – Aggregate supply approach
Saving – Investment approach

Question 2.
Define “Unemployment”?
Answer:
Unemployment:
When there are people, who are willing to work and able to work but cannot find suitable jobs.

Question 3.
Define “Marginal propensity to consume”?
Answer:
Marginal Propensity to Consume is the additional consumption due to an additional unit of income.

Question 4.
Write the types of unemployment?
Answer:
Types of unemployment:

Cyclical Unemployment
Frictional Unemployment
Technical Unemployment
Disguised Unemployment
Seasonal Unemployment
Educated Unemployment
Structural Unemployment

Part – C
Answer The Following Questions In One Paragraph.

Question 1.
Explain the Aggregate Demand Function with Diagram?
Answer:

In the Keynesian model, output is determined mainly by aggregate demand.
The aggregate demand is the amount of money which entrepreneurs expect to get by selling the output produced by the number of labourers employed.
Therefore, it is the expected income or revenue from the sale of output at different levels of employment.
- Aggregate demand has the following four components:
  - Consumption demand
  - Investment demand
  - Government expenditure and
  - Net Export (export – import)
The desired or planned demand (spending) is the amount that households, firms, the governments and the foreign purchasers would like to spend on domestic output.
In other words, desired demand in the economy is the sum total of desired private consumption expenditure, desired investment expenditure, desired government spending and desired net exports (difference between exports and imports).
Thus, the desired spending is called aggregate spending (demand), and can be expressed as:
AD = C + I + G + (X – M)
The diagram explains that aggregate demand price increases or decreases with an increase or decrease in the volume of employment.
Aggregate demand curve increases at an increasing rate in the beginning and then increases at a decreasing rate.
This shows that as income increases owing to increase in employment, expenditure of the economy increases at a decreasing rate.

Samacheer Kalvi 12th Economics Chapter 3 Solutions Theories of Employment and Income

Question 2.
Aggregate Supply Function meaning and components?
Answer:

Aggregate supply function is an increasing function of the level of employment.
Aggregate supply refers to the value of total output of goods and services produced in an economy in a year.
In other words, aggregate supply is equal to the value of national product, i.e., national income.

The components of aggregate supply are:

Aggregate (desired) consumption expenditure (C)
Aggregate (desired) private savings (S)
Net tax payments (T) (Total tax payment to be received by the government minus transfer payments, subsidy and interest payments to be incurred by the government) and (iv) Personal (desired) transfer payments to the foreigners (Rf) (e.g. Donations to international relief efforts)

Question 3.
Describe the features of classicism?
Answer:

Long – run equilibrium
Saving is a social virtue.
The function of money is to act as a medium of exchange
Micro foundation to macro problems
Champions of Laissez-fair policy
Applicable only to the full employment situation.
Capitalism is well and good.
Balanced budget
The equality between saving and investment is achieved through changes of rate of interest.
Rate of interest is determined by saving and investment.
Rate of interest is a stock.
Supply creates its own demand.
Rate of interest is a reward for saving.

Part – D
Answer The Following Questions In One Page.

Question 1.
Describe the Say’s Law of Market?
Answer:

Say’s law of markets is the core of the classical theory of employment.
J.B.Say (1776 – 1832) was a French Economist and an industrialist.
He was influenced by the writings of Adam Smith and David Ricardo.
J.B. Say enunciated the proposition that “Supply creates its own demand”.
Hence there cannot be general over production or the problem of unemployment in the economy.
According to Say, “When goods are produced by firms in the economy, they pay reward to the factors of production.
The households after receiving rewards of the factors of production spend the amount on the purchase of goods and services produced by them.
Therefore, each product produced in the economy creates demand equal to its value in the market.
In short, this classical theory explains that “A person receives his income from production which is spent on the purchase of goods and services produced by others.
For the economy as a whole, therefore, total production equals total income.

Question 2.
Explain the features of Keynesianism?
Answer:

Short – run equilibrium
Saving is a vice
The function of money is a medium of exchange on the one side and a store of value on the other side.
Macro approach to national problems
State intervention is advocated.
Applicable to all situations – full employment and less than full employment.
Capitalism has inherent contradictions.
Budgeting should be adjusted to the requirements of economy.
The equality between saving and investment is advanced through changes in income.
Rate of interest is determined by the demand for and supply of money.
Rate of interest is a flow.
Demand creates its own supply.
Rate of interest is a reward for parting with liquidity.

Question 3.
Describe the Effective demand?
Answer:

The starting point of Keynes theory of employment and income is the principle of effective demand.
Effective demand denotes money actually spent by the people on products of industry.
The money which entrepreneurs receive is paid in the form of rent, wages, interest and profit.
Therefore effective demand equals national income.
An increase in the aggregate effective demand would increase the level of employment.
A decline in total effective demand would lead to unemployment.
Therefore, total employment of a country can be determined with the help of total demand ‘ of a country.
According to the Keynes theory of employment, “Effective demand signifies the money spent on consumption of goods and services and on investment.
The total expenditure is equal to the national income, which is equivalent to the national output”.
The relationship between employment and output of an economy depends upon the level of effective demand which is determined by the forces of aggregate supply and aggregate demand.
ED = Y = C + I = Output = Employment
Effective demand determines the level of employment in the economy.
When effective demand increases, employment will increase.
When effective demand decreases, the level employment will decline.
The effective demand will be determined by two determinants namely consumption and investment expenditures.
The consumption function depends upon income of the people and marginal propensity to consume.
According to Keynes, if income increases, consumption will also increase but by less than the increase in income.

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Samacheer Kalvi 12th Economics Solutions Chapter 4 Consumption and Investment Functions

April 24, 2024

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Tamilnadu Samacheer Kalvi 12th Economics Solutions Chapter 4 Consumption and Investment Functions

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Samacheer Kalvi 12th Economics Consumption and Investment Functions Text Book Back Questions and Answers

Part – A
Multiple Choice Questions.

Question 1.
The average propensity to consume is measured by –
(a) C / Y
(b) C × Y
(c) Y / C
(d) C + Y
Answer:
(a) C / Y

Question 2.
An increase in the marginal propensity to consume will:
(a) Lead to consumption function becoming steeper
(b) Shift the consumption function upwards
(c) Shift the consumption function downwards
(d) Shift savings function upwards
Answer:
(a) Lead to consumption function becoming steeper.

Question 3.
If the Keynesian consumption function is C = 10 + 0.8 Y then, if disposable income is Rs 1000, what is amount of total consumption?
(a) ₹ 0.8
(b) ₹ 800
(c) ₹ 810
(d) ₹ 0.81
Answer:
(c) ₹ 810

Question 4.
If the Keynesian consumption function is C = 10 + 0.8 Y then, when disposable income is Rs 100, what is the marginal propensity to consume?
(a) ₹ 0.8
(b) ₹ 800
(c) ₹ 810
(d) ₹ 0.81
Answer:
(a) ₹ 0.8

Question 5.
If the Keynesian consumption function is C = 10 + 0.8 Y then, and disposable income is ₹ 100, what is the average propensity to consume?
(a) ₹ 0.8
(b) ₹ 800
(c) ₹ 810
(d) ₹ 0.9
Answer:
(d) ₹ 0.9

Question 6.
As national income increases –
(a) The APC falls and gets nearer in value to the MPC.
(b) The APC increases and diverges in value from the MPC.
(c) The APC stays constant
(d) The APC always approaches infinity.
Answer:
(a) The APC falls and gets nearer in value to the MPC.

Question 7.
As increase in consumption at any given level of income is likely to lead –
(a) Higher aggregate demand
(b) An increase in exports
(c) A fall in taxation revenue
(d) A decrease in import spending
Answer:
(a) Higher aggregate demand

Question 8.
Lower interest rates are likely to:
(a) Decrease in consumption
(b) increase cost of borrowing
(c) Encourage saving
(d) increase borrowing and spending
Answer:
(d) increase borrowing and spending

Question 9.
The MPC is equal to:
(a) Total spending / total consumption
(b) Total consumption / total income
(c) Change in consumption / change in income
(d) None of the above
Answer:
(c) Change in consumption / change in income

Question 10.
The relationship between total spending on consumption and the total income is the –
(a) Consumption function
(b) Savings function
(c) Investment function
(d) aggregate demand function
Answer:
(a) Consumption function

Question 11.
The sum of the MPC and MPS is –
(a) 1
(b) 2
(c) 0.1
(d) 1.1
Answer:
(a) 1

Question 12.
As income increases, consumption will –
(a) fall
(b) not change
(c) fluctuate
(d) increase
Answer:
(d) increase

Question 13.
When investment is assumed autonomous the slope of the AD schedule is determined by the –
(a) marginal propensity to invest
(b) disposable income
(c) marginal propensity to consume
(d) average propensity to consume
Answer:
(c) marginal propensity to consume

Question 14.
The multiplier tells us how much changes after a shift in –
(a) Consumption, income
(b) investment, output
(c) savings, investment
(d) output, aggregate demand
Answer:
(d) output, aggregate demand

Question 15.
The multiplier is calculated as –
(a) 1 / (1 – MPC)
(b) 1 / MPS
(c) 1 / MPC
(d) a and b
Answer:
(d) a and b

Question 16.
It the MPC is 0.5, the multiplier is –
(a) 2
(b) 1/2
(c) 0.2
(d) 20
Answer:
(a) 2

Question 17.
In an open economy import ………………………. the value of the multiplier
(a) Reduces
(b) increase
(c) does not change
(d) changes
Answer:
(a) Reduces

Question 18.
According to Keynes, investment is a function of the MEC and –
(a) Demand
(b) Supply
(c) Income
(d) Rate of interest
Answer:
(d) Rate of interest

Question 19.
The term super multiplier was first used by –
(a) J.R.Hicks
(b) R.G.D. Allen
(c) Kahn
(d) Keynes
Answer:
(a) J.R.Hicks

Question 20.
The term MEC was introduced by –
(a) Adam Smith
(b) J.M. Keynes
(c) Ricardo
(d) Malthus
Answer:
(b) J.M. Keynes

Part – B
Answer The Following Questions In One or Two Sentences

Question 21.
What is consumption function?
Answer:
Meaning of Consumption Function:

1. The consumption function or propensity to consume refers to income consumption relationship. It is a “functional relationship between two aggregates viz., total consumption and gross national income.”

2. Symbolically, the relationship is represented as C = f (Y)
Where,
C = Consumption; Y = Income; f = Function

3. Thus the consumption function indicates a functional relationship between C and Y, where C is the dependent variable and Y is the independent variable, i.e., C is determined by Y. This relationship is based on the ceteris paribus (other things being same) assumption, as only income consumption relationship is considered and all possible influences on consumption are held constant.
Samacheer Kalvi 12th Economics Chapter 4 Consumption and Investment Functions

Question 22.
What do you mean by propensity to consume?
Answer:

2. Symbolically, the relationship is represented as C = f(Y) Where, C = Consumption; Y = Income; f = Function

Question 23.
Define average propensity to consume (APC)?
Answer:
Average Propensity to Consume:

1. The average propensity to consume is the ratio of consumption expenditure to any particular level of income.” Algebraically it may be expressed as under:
Where, C = Consumption; Y = Income
APC = $\frac{C}{Y}$
Where, C = Consumption; Y = Income.

Question 24.
Define marginal propensity to consume (MPC)?
Answer:
Marginal Propensity to Consume:

1. The marginal propensity to consume may be defined as the ratio of the change in the consumption to the change in income. Algebraically it may be expressed as under:
MPC = $\frac { \Delta C }{ \Delta Y } $
Where, ∆C = Change in Consumption; ∆Y = Change in Income
MPC is positive but less than unity, 0 < $\frac { \Delta C }{ \Delta Y } $ < 1.

Question 25.
What do you mean by propensity to save?
Answer:

Thus the consumption function measures not only the amount spent on consumption but also the amount saved.
This is because the propensity to save is merely the propensity not to consume.
The 45° line may therefore be regarded as a zero – saving line, and the shape and position of the C curve indicate the division of income between consumption and saving.

Question 26.
Define average propensity to save (APS)?
Answer:
Average Propensity to Save (APS):

The average propensity to save is the ratio of saving to income.
APS is the quotient obtained by dividing the total saving by the total income. In other words, it is the ratio of total savings to total income. It can be expressed algebraically in the form of equation as under
APS = $\frac{S}{Y}$ Where, S = Saving; Y = Income

Question 27.
Define Marginal Propensity to Save (MPS)?
Answer:
Marginal Propensity to Save (MPS):

1. Marginal Propensity to Save is the ratio of change in saving to a change in income.

2. MPS is obtained by dividing change in savings by change in income. It can be expressed algebraically as MPS = $\frac { \Delta S }{ \Delta Y } $
∆S = Change in Saving; ∆Y = Change in Income
Since MPC + MPS = 1
MPS = 1 – MPC and MPC = 1 – MPS.

Question 28.
Define Multiplier?
Answer:

The multiplier is defined as the ratio of the change in national income to change in investment.
If AI stands for increase in investment and AY stands for resultant increase in income, the multiplier K =AY/AI.
Since AY results from AI, the multiplier is called investment multiplier.

Question 29.
Define Accelerator?
Answer:

“The accelerator coefficient is the ratio between induced investment and an initial change in consumption.”
Assuming the expenditure of ₹50 crores on consumption goods, if industries lead to an investment of ₹100 crores in investment goods industries, we can say that the accelerator is 2.
Accelerator = $\frac { 100 }{ \Delta Y } $ = 2

Part – C
Answer The Following Questions In One Paragraph.

Question 30.
State the propositions of Keynes’s Psychological Law of Consumption?
Answer:
Propositions of the Law:
This law has three propositions:
1. When income increases, consumption expenditure also increases but by a smaller amount. The reason is that as income increases, we wants are satisfied side by side, so that the need to spend more on consumer goods diminishes. So, the consumption expenditure increases with increase in income but less than proportionately.

2. The increased income will be divided in some proportion between consumption expenditure and saving. This follows from the first proposition because when the whole • of increased income is not spent on consumption, the remaining is saved. In this way, consumption and saving move together.

3. Increase in income always leads to an increase in both consumption and saving. This means that increased income is unlikely to lead to fall in either consumption or saving. Thus with increased income both consumption and saving increase.

Question 31.
Differentiate autonomous and induced investment?
Answer:
Autonomous Investment:

Independent
Income inelastic
Welfare motive

Induced Investment:

Planned
Income elastic
Profit Motive

Question 32.
Explain any three subjective and objective factors influencing the consumption function?
Answer:
Subjective Factors:

The motive of precaution: To build up a reserve against unforeseen contingencies. e.g. Accidents, sickness. ,
The motive of foresight: The desire to provide for anticipated future needs. e.g. Old age.
The motive of calculation: The desire to enjoy interest and appreciation. Consumption and Investment Functions.

Objective Factors:
1. Income Distribution:
If there is large disparity between rich and poor, the consumption is low because the rich people have low propensity to consume and high propensity to save.

2. Price level:
Price level plays an important role in determining the consumption function. When the price falls, real income goes up; people will consume more and propensity to save of the
society increases.

3. Wage level:
Wage level plays an important role in determining the consumption function and there is positive relationship between wage and consumption. Consumption expenditure increases with the rise in wages. Similar is the effect with regard to windfall gains.

Question 33.
Mention the differences between accelerator and multiplier effect?
Answer:
Accelerator Effect Multiplier Effect:

1. Accelerator is the numerical value of the relation between an increase in consumption and the resulting increasing in Investment. Multiplier is the ration of the change in national income to change in Investment.

2. Accelerator (β) = $\frac { \Delta I }{ \Delta C } $
ΔI = Change in Investment
ΔC = Change in consumption demand Multiplier (K) = $\frac { \Delta I }{ \Delta C } $
ΔI = Increase in Investment ΔY = Increase in Income ΔY results from ΔI

3. Accelerator Effects are –

Increase in consumer demand.
Films get close to fill capacity.
Film invest to meet rising demand. Multiplier Effects are

Multiplier Effect:
1. Multiplier is the ration of the change in national income to change in Investment.

2. Multiplier:
Multiplier (K) = $\frac { \Delta Y }{ \Delta I } $
ΔI = Increase in Investment
ΔY = Increase in Income
ΔY results from ΔI

Multiplier Effects are:

Positive Multiplier an initial increases is an injection (or a decrease in a leakage) leads to a greater final increase in real GDP.
Negative Multiplier an initial increases in an injection (or an increase in a leakage) leads to a greater final decrease in real GDP.

Question 34.
State the concept of super multiplier?
Answer:
Super Multiplier: (k and β interaction):

The super multiplier is greater than simple multiplier which includes only autonomous investment and no induced investment, while super multiplier includes induced investment.
In order to measure the total effect of initial investment on income, Hicks has combined the k and β mathematically and given it the name of the Super Multiplier.
The super multiplier is worked out by combining both induced consumption and induced investment.

Question 35.
Specify the limitations of the multiplier?
Answer:

There is change in autonomous investment.
There is no induced investment
The marginal propensity to consume is constant.
Consumption is a function of current income.
There are no time lags in the multiplier process.
Consumer goods are available in response to effective demand for them.
There is a closed economy unaffected by foreign influences.
There are no changes in prices.
There is less than full employment level in the economy.

Part – D
Answer The Following Questions In About A Page.

Question 36.
Explain Keynes psychological law of consumption function with diagram?
The three propositions of the law:
Samacheer Kalvi 12th Economics Solutions Chapter 4 Consumption and Investment Functions

Proposition (1):
Income increases by ₹ 60 crores and the increase in consumption is by ₹ 50 crores.

Proposition (2):
The increased income of ₹ 60 crores in each case is divided in some proportion between consumption and saving respectively, (i.e., ₹ 50 crores and ₹ 10 crores).

Proposition (3):
As income increases consumption as well as saving increase. Neither consumption nor saving has fallen. Diagrammatically, the three propositions are explained in figure. Here, income is measured horizontally and consumption and saving are measured on the vertical axis. C is the consumption function curve and 45° line represents income consumption equality.
Samacheer Kalvi 12th Economics Solutions Chapter 4 Consumption and Investment Functions

Proposition (1):
When income increases from 120 to 180 consumption also increases from 120 to 170 but the increase in consumption is less than the increase in income, 10 is saved.

Proposition (2):
When income increases to 180 and 240, it is divided in some proportion between consumption by 170 and 220 and saving by 10 and 20 respectively.

Proposition (3):
Increases in income to 180 and 240 lead to increased consumption 170 and 220 and increased saving 20 and 10 than before. It is clear from the widening area below the C curve and the saving gap between 45° line and C curve.

Question 37.
Briefly explain the subjective and objective factors of consumption function?
Answer:
Subjective Factors:

The motive of precaution: To build up a reserve against unforeseen contingencies. e.g. Accidents, sickness
The motive of foresight: The desire to provide for anticipated future needs, e.g. Old age
The motive of calculation: The desire to enjoy interest and appreciation.
The motive of improvement: The desire to enjoy for improving standard of living.
The motive of financial independence.
The motive of enterprise (desire to do forward trading).
The motive of pride.(desire to bequeath a fortune)
The motive of avarice.(purely miserly instinct)

2. Price level:

Price level plays an important role in determining the consumption function.
When the price falls, real income goes up; people will consume more and propensity to save of the society increases.

3. Wage level:

Wage level plays an important role in determining the consumption function and there is positive relationship between wage and consumption.
Consumption expenditure increases with the rise in wages.
Similar is the effect with regard to windfall gains.

4. Interest rate:

Rate of interest plays an important role in determining the consumption function.
Higher rate of interest will encourage people to save more money and reduces consumption.

5. Fiscal Policy:
When government reduces the tax the disposable income rises and the propensity to consume of community increases.

6. Consumer credit:

The availability of consumer credit at easy installments will encourage households to buy consumer durables like automobiles, fridge, computer.
This pushes up consumption.

7. Demographic factors:

Ceteris paribus, the larger the size of the family, the grater is the consumption.
Besides size of family, stage in family life cycle, place of residence and occupation affect the consumption function.

8. Duesenberry hypothesis:
Duesenberry has made two observations regarding the factors affecting consumption.

The consumption expenditure depends not only on his current income but also past income and standard of living.
Consumption is influenced by demonstration effect. The consumption standards of low income groups are influenced by the consumption standards of high income groups.

9. Windfall Gains or losses:
Unexpected changes in the stock market leading to gains or losses tend to shift the consumption function upward or downward.

Question 38.
Illustrate the working of Multiplier?
Answer:
Working of Multiplier:

Suppose the Government undertakes investment expenditure equal to ₹ 100 crore on some public works, by way of wages, price of materials etc.
Thus income of labourers and suppliers of materials increases by ₹ 100 crore. Suppose the MPC is 0.8 that is 80 %.
A sum of ₹ 80 crores is spent on consumption (A sum of ₹ 20 Crores is saved).
As a result, suppliers of goods get an income of ₹ 80 crores.
They intum spend ₹ 64 crores (80% of ₹ 80 cr).
In this manner consumption expenditure and increase in income act in a chain like maimer.

The final result is ∆Y = 100 + 100 × 4/5 + 100 × [4/5]² + 100 × [4/5]³ or,
∆Y = 100 + 100 × 0.8 + 100 × (0.8)² + 100 × (0.8)³
= 100 + 80 + 64 + 51.2… = 500 .
that is 100 × 1/1 – 4/5
100 × 1/1/5
100 × 5 = ₹ 500 crores
For instance if C = 100 + 0.8Y, I = 100,
Then Y = 100 + 0.8Y + 100
0.2Y = 200
Y = 200/0.2 = 1000 → Point B
If I is increased to 110, then
0.2Y = 210
Y = 210/0.2 = 1050 → Point D
For ₹ 10 increase in I, Y has increased by ₹ 50.
This is due to multiplier effect.
At point A, Y = C = 500
C = 100 + 0.8 (500) = 500; S = 0
At point B, Y = 1000
C = 100 + 0.8 (1000) = 900; S = 100 = I At point D, Y = 1050
C = 100 + 0.8 (1050) = 940; S = 110 = I
When I is increased by 10, Y increases by 50.
This is multiplier effect (K = 5)
K = $\frac{1}{0.2}$ = 5

Question 39.
Explain the operation of the Accelerator?
Answer:
Operation of the Acceleration Principle:

Let us consider a simple example. The operation of the accelerator may be illustrated as follows.
Let us suppose that in order to produce 1000 consumer goods, 100 machines are required.
Also suppose that working life of a machine is 10 years.
This means that every year 10 machines have to be replaced in order to maintain the constant flow of 1000 consumer goods. This might be called replacement demand.
Suppose that demand for consumer goods rises by 10 percent (i.e. from 1000 to 1100).
This results in increase in demand for 10 more machines.
So that total demand for machines is 20. (10 for replacement and 10 for meeting increased demand).
It may be noted here a 10 percent increase in demand for consumer goods causes a 100 percent increase in demand for machines (from 10 to 20).
So we can conclude even a mild change in demand for consumer goods will lead to wide change in investment.

Diagrammatic illustration:
Operation of Accelerator.

SS is the saving curve. II is the investment curve. At point E₁ the economy is in equilibrium with OY₁ income. Saving and investment are equal at OY₁ Now, investment is increased from OI₂ to OI₄.
This increases income from OY₁ to OY₃, the equilibrium point being E₃ If the increase in investment by I₂ I₄ is purely exogenous, then the increase in income by Y₁ Y₃ would have been due to the multiplier effect.
But in this diagram it is assumed that exogenous investment is only by I, I3 and induced investment is by I₃I₄.
Therefore, increase in income by Y₁ Y₂ is due to the multiplier effect and the increase in income by Y₂ Y₃ is due to the accelerator effect.

Samacheer Kalvi 12th Economics Solutions Chapter 4 Consumption and Investment Functions

Question 40.
What are the differences between MEC and MEI?
Answer:
Marginal Efficiency of Capital (MEC):

It is based on a given supply price for capital.
It represents the rate of return on all successive units of capital without regard to existing capital.
The capital stock is taken on the X axis of diagram.
It is a “stock” concept.
It determines the optimum capital stock in an economy at each level of interest rate.

Marginal Efficiency of Investment (MEI):

It is based on the induced change in the price due to change in the demand for capital.
It shows the rate of return on just those units of capital over and above the existing capital stock.
The amount of investment is taken on the X – axis of diagram.
It is a “flow” concept.
It determines the net investment of the economy at each interest rate given the capital stock.

Samacheer Kalvi 12th Economics Consumption and Investment Functions Additional Questions and Answers

part – A
I. Multiple Choice Questions.

Question 1.
Price level plays an important role in determining the ……………………
(a) Consumption function
(b) Income function
(c) Finance function
(d) Price function
Answer:
(a) Consumption function

Question 2.
The progressive tax system increases the ……………………….. of the people by altering the income distribution in favour of poor?
(a) price level
(b) wage level
(c) propensity to consume
(d) Fiscal policy
Answer:
(c) propensity to consume

Question 3.
…………………….. means purchase of stocks and shares, debentures, government bonds and equities?
(a) Consumption
(b) Investment
(c) Finance
(d) Saving
Answer:
(b) Investment

Question 4.
…………………… is influenced by demonstration effect.
(a) Investment
(b) Interest
(c) Expenditure
(d) Consumption
Answer:
(d) Consumption

Question 5.
Additional investment that is independent of income is called ……………………
(a) Autonomous Investment
(b) Autonomous Consumption
(c) Average Investment
(d) Marginal Investment
Answer:
(a) Autonomous Investment

Question 6.
Induced investment is motivated?
(a) Investment
(b) Capital
(c) Saving
(d) Profit
Answer:
(d) Profit

Question 7.
MEI is the expected rate of return on investment as additional units of ……………………
(a) Saving
(b) Investment
(c) Consumption
(d) Expenditure
Answer:
(b) Investment

Question 8.
Dynamic multiplier is also known as ……………………
(a) Sequence multiplier
(b) Static multiplier
(c) Double multiplier
(d) Single multiplier
Answer:
(a) Sequence multiplier

Question 9.
The combined effect of interaction of multiplier and accelerator is called ……………………
(a) Super accelerator
(b) Super multiplier
(c) Accelerator
(d) Multiplier
Answer:
(b) Super multiplier

Question 10.
The tendency to initiate Superior consumption pattern is called ……………………
(a) Accelerator effect
(b) Multiplier effect
(c) Super Multiplier effect
(d) Demonstration effect
Answer:
(d) Demonstration effect

Question 11.
The multiplier is the reciprocal of one minus ……………………
(a) MPC
(b) MPS
(c) Multiplier
(d) Accelerator
Answer:
(a) MPC

Question 12.
The concept of multiplier was first developed by ……………………
(a) J.M. Keynes
(b) David Ricardo
(c) R.F. Khan
(d) J.B. Say
Answer:
(c) R.F. Khan

Question 13.
…………………… the larger size of the family, the greater is the consumption?
(a) Demographic factors
(b) Income Distribution
(c) Duesenberry hypothesis
(d) Wage level
Answer:
(b) Income Distribution

Question 14.
MPS is the ratio of change in saving to a change in ……………………
(a) profit
(b) money
(c) finance
(d) income
Answer:
(d) income

Question 15.
Consumption function is called the relationship between ……………………….. and Income?
(a) Money
(b) Consumption
(c) Finance
(d) Investment
Answer:
(b) Consumption

Question 16.
Consumer’s surplus is useful to the Finance Minister in formulating ……………………….. policies?
(a) Surplus
(b) Consumption
(c) Taxation
(d) Income
Answer:
(c) Taxation

Question 17.
Consumer surplus is called potential price – ……………………………. price?
(a) real
(b) actual
(c) normal
(d) high
Answer:
(b) actual

Question 18.
Dynamic multiplier is also known as ………………………. Multiplier.
(a) Sequence
(b) Static
(c) Timeless
(d) Logical
Answer:
(a) Sequence

Question 19.
Static Multiplier is otherwise known as …………………………… Multiplier.
(a) Dynamic
(b) Leakage
(c) Simultaneous
(d) Multi effect
Answer:
(c) Simultaneous

Question 20.
The propensity to consume refers to the portion of Income spent on ……………………….
(a) Income
(b) Profit
(c) Expenditure
(d) Consumption
Answer:
(d) Consumption

Question 21.
………………………. redefined it as investment multiplier.
(a) R.K. Khan
(b) David Ricardo
(c) J.M. Keynes
(d) Marshall
Answer:
(c) J.M. Keynes

Question 22.
Accelerator Model was made by ……………………
(a) J.M. Keynes
(b) J.M. Clark
(c) R.F. Khan
(d) Marshall
Answer:
(b) J.M. Clark

Question 23.
The multiplier tells us …………………………. changes after a shift in ……………………
(a) income
(b) investment
(c) aggregate demand
(d) savings
Answer:
(c) aggregate demand

Question 24.
The simple accelerated model was made by J.M. Clark in ……………………
(a) 1915
(b) 1916
(c) 1914
(d) 1917
Answer:
(d) 1917

II. Match the following and choose the correct answer by using codes given below

Question 1.
A. Consumption function – (i) Consmption increased
B. Induced Investment – (ii) Borrowings
C. Income Increases – (iii) Subjective and objective
D. Autonomous consumption – (iv) Profit motive
Codes:
(a) A (iii) B (iv) C (i) D (ii)
(b) A (iv) B (i) C (ii) D (iii)
(c) A (i) B (ii) C (iii) D (iv)
(d) A (ii) B (iii) C (iv) D (i)
Answer:
(a) A (iii) B (iv) C (i) D (ii)

Question 2.
A. MPS – measured – (i) K = 1/MPS
B. Multiplier developed by – (ii) MEC
C. Investment depends on – (iii) ∆S/∆Y
D. Value of multiplier – (iv) R.F. Khan
Codes:
(a) A (i) B (ii) C (iv) D (iii)
(b) A (ii) B (iii) C (i) D (iv)
(c) A (iii) B (iv) C (ii) D (i)
(d) A (iv) B (i) C (iii) D (ii)
Answer:
(c) A (iii) B (iv) C (ii) D (i)

Question 3.
A. Reduced Investment – (i) 1930
B. Keynes employment dependes on – (ii) Highest interest rate
C. Fall in investment – (iii) Zero
D. Long fun autonomous consumption will – (iv) Investment
Codes:
(a) A (i) B (iii) C (iv) D (ii)
(b) A (ii) B (iv) C (i) D (iii)
(c) A (iii) B (i) C (ii) D (iv)
(d) A (iv) B (ii) C (iii) D (i)
Answer:
(b) A (ii) B (iv) C (i) D (iii)

Question 4.
A. MPS – (i) AC/AY
B. MPC – (ii) C/Y
C. APS – (iii) S/Y
D. APC – (iv) AS/AY
Codes:
(a) A (iv) B (i) C (iii) D (ii)
(b) A (i) B (ii) C (iv) D (iii)
(c) A (ii) B (iii) C (i) D (iv)
(d) A (iii) B (iv) C (ii) D (i)
Answer:
(a) A (iv) B (i) C (iii) D (ii)

Question 5.
A. Investment means – (i) Expenditure on capital formation
B. Uses of multiplier – (ii) Consumption forgone
C. Saving is – (iii) Achieve full employment
D. Autonomous investment – (iv) Stocks and shares
Codes:
(a) A (ii) B (i) C (iv) D (iii)
(b) A (iii) B (ii) C (iii) D (iv)
(c) A (iv) B (iii) C (ii) D (i)
(d) A (i) B (iv) C (i) D (ii)
Answer:
(c) A (iv) B (iii) C (ii) D (i)

III. State whether the statements are true or false.

Question 1.
(i) Keynes propounded the fundamental psychological law of consumption.
(ii) J.M. Keynes has divided factors influencing the consumption function.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 2.
(i) The kinds of multiplier is called Tax Multiplier, Employment Multiplier, Foreign trade Multiplier, Investment Multiplier.
(ii) Investment means money collecting.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(d) (i) is false but (ii) is true

Question 3.
(i) The term investment means purchase of stocks and shares, debentures, government bonds and equities.
(ii) The term Investment means expenditure on capital formation.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(c) (i) is true but (ii) is false

Question 4.
(i) Leakages of multiplier is payment only.
(ii) Leakages of multiplier limitation is called full employment situation.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(d) (i) is false but (ii) is true

Question 5.
(i) The types of Investment is called Autonomous Investment, Induced Investment.
(ii) Induced Investment is the expenditure on fixed assets and stocks.

(a) Both (i) and (ii) are true
(b) Both 0) and (if) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

IV. Which of the following is correctly matched:

Question 1.
(a) J.M. Clark – Ceteris Paribus
(b) J.M. Keynes – Psychological law of consumption
(c) R.F. Khan – Accelerator model
(d) Duesenberry – Laissez – faire
Answer:
(b) J.M. Keynes – Psychological law of consumption

Question 2.
(a) Induced Investment – Profit motive
(b) MEC – Autonomous Investment
(c) MEI – Technology
(d) MPC – Accelerator
Answer:
(a) Induced Investment – Profit motive

Question 3.
(a) Dynamic Multiplier – Employment
(b) Static Multiplier – Wealth
(c) Accelerator Model – J.M. Clark
(d) Leakage Multiplier – Investment goods
Answer:
(c) Accelerator Model – J.M. Clark

Question 4.
(a) Afltalion – 1909
(b) Hawtrey – 1914
(c) Bickerdike – 1915
(d) J.M. Clark – 1916
Answer:
(a) Afltalion – 1909

Question 5.
(a) Aggregate Income – C
(b) Consumption expenditure – I_A
(c) Autonomous Investment – Y
(d) Induced Private Investment – I_P
Answer:
(d) Induced Private Investment – I_P

V. Which of the following is not correctly matched

Question 1.
(a) Static multiplier – Simultaneous multiplier
(b) Dynamic multiplier – Sequence multiplier
(c) Leakage multiplier – Timeless multiplier
(d) Kinds of multiplier – Tax multiplier
Answer:
(c) Leakage multiplier – Timeless multiplier

Question 2.
(a) Ratio of the consumption – APC expenditure to Income
(b) Ratio of change in consumption – MPC to change in Income
(c) Ratio of the saving to Income – APS
(d) Ratio of change in saving to change in Income – PSM change in Income
Answer:
(d) Ratio of change in saving to change in Income – PSM change in Income

Question 3.
(a) Demonstration Effect – Superior consumption pattern
(b) Subjective factors – Psychological feeling
(c) Objective factors – Real and Measurable
(d) Super multiplier – Investment demand
Answer:
(d) Super multiplier – Investment demand

Question 4.
(a) Average propensity to consume – C/Y
(b) Marginal propensity to consume – AC/AY
(c) Average propensity to consume – S/Y
(d) Marginal propensity to save – AY/AS
Answer:
(d) Marginal propensity to save – AY/AS

Question 5.
(a) The motive of precaution – Accidents, Sickness
{b) The motive of foresight – Old age
(c) The motive of improvement – Improve standard of living
(d) The motive of calculation – Money collecting
Answer:
(d) The motive of calculation – Money collecting

VI. Pick the odd one out.

Question 1.
(a) ∆C – Change in consumption
(b) ∆Y – Change in expenditure
(c) ∆S – Change in saving 4
(d) ∆Y – Change in income
Answer:
(b) ∆Y – Change in expenditure

Question 2.
(a) APC – Algebraically Propensity to Consume
(b) MPC – Marginal Propensity to Consume
(c) APS – Average Propensity to Consume
(d) MPS – Marginal Propensity to Save
Answer:
(a) APC – Algebraically Propensity to Consume

Question 3.
Keynes’s Law is based on the Assumptions.
(a) Ceteris paribus
(b) Existence of Normal conditions
(c) Existence of a Laissez – Faire
(d) Existence of a Technical attributes
Answer:
(d) Existence of a Technical attributes

Question 4.
Investment means
(a) Purchase of stocks and shares
(b) Debentures
(c) Government bonds and equities
(d) Bank amount
Answer:
(d) Bank amount

Question 5.
MEC – Short Run Factors
(a) Supply for the product
(b) Liquid Assets
(c) Sudden changes in Income
(d) Current rate of Investment
Answer:
(a) Supply for the product

VII. Assertion and Reason.

1. Assertion (A): Keynes Law of propositions – when Income increases, consumption expenditure also increases but by a smaller amount.
Reason (R): Keynes Law of propositions – Increase in Income always lead to an increase in both consumption and saving.

Question 2.
Assertion (A): J.M. Keynes has influencing consumption function into subjective factors are the Internal factors related to psychological feelings.
Reason (R): J.M. Keynes has influencing consumption function into objective factors are Internal factors are not measurable.

Question 3.
Assertion (A): Autonomous Investment is the expenditure on capital formation.
Reason (R): Autonomous Investment is Independent of the change in Income, rate of Interest or rate of profit.

Question 4.
Assertion (A): MEC – depends on the Demand yield from a capital asset.
Reason (R): MEC – depends on the Supply price of a capital asset.

Question 5.
Assertion (A): Keynes theory of the Multiplier Assumption is change in autonomous Investment.
Reason (R): Keynes theory of the Multiplier Assumption is no Induced Investment.

(а) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(а) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’

Part – B
Answer The Following Questions In One or Two Sentences.

Question 1.
Write “Propensity to consume” Equations?
Answer:
(i) The Average Propensity to Consume = $\frac{c}{y}$
(ii) The Marginal Propensity to Consume = $\frac{∆c}{∆y}$
(iii) The Average Propensity to Save = $\frac{x}{y}$
(iv) The Marginal Propensity to Save = $\frac{∆s}{∆y}$

Question 2.
Define “Ceteris paribus”?
Answer:
Ceteris paribus (constant extraneous variables):
The other variables such as income distribution, tastes, habits, social customs, price movements, population growth, etc. do not change and consumption depends on income alone.

Question 2.
Define “Laissez-Faire” – Capitalist Economy?
Answer:
Existence of a Laissez – faire Capitalist Economy:
The law operates in a rich capitalist economy where there is no government intervention. People should be free to spend increased income. In the case of regulation of private enterprise and consumption expenditures by the State, the law breaks down.

Question 3.
What do you mean “Windfall Gains” or “Losses”?
Answer:
Windfall Gains or losses:
Unexpected changes in the stock market leading to gains or losses tend to shift the consumption function upward or downward.

Question 4.
Define “Autonomous consumption”?
Answer:
Autonomous Consumption:
Autonomous consumption is the minimum level of consumption or spending that must take place even if a consumer has no disposable income, such as spending for . basic necessities.

Part – C
Answer the Following Questions In One Paragraph.

Question 1.
Explain the Keynes Psychological Law’ of consumption assumptions?
Answer:
Keynes’s Law is based on the following assumptions:
1. Ceteris paribus (constant extraneous variables):
The other variables such as income distribution, tastes, habits, social customs, price movements, population growth, etc. do not change and consumption depends on income alone.

2. Existence of Normal Conditions:

The law holds good under normal conditions.
If, however, the economy is faced with abnormal and extraordinary circumstances like war, revolution or hyperinflation, the law will not operate.
People may spend the whole of increased income on consumption.

3. Existence of a Laissez – faire Capitalist Economy:

The law operates in a rich capitalist economy where there is no government intervention.
People should be free to spend increased income.
In the case of regulation of private enterprise and consumption expenditures by the State, the law breaks down.

Question 2.
Explain the Marginal Efficiency of capital?
Answer:
Marginal Efficiency of Capital:

MEC was first introduced by J.M Keynes in 1936 as an important determinant of autonomous investment.
The MEC is the expected profitability of an additional capital asset.
It may be defined as the highest rate of return over cost expected from the additional unit of capital asset.
Meaning of Marginal Efficiency of Capital (MEC) is the rate of discount which makes the discounted present value of expected income stream equal to the cost of capital.

MEC depends on two factors:

The prospective yield from a capital asset.
The supply price of a capital asset.

Factors Affecting MEC:
Samacheer Kalvi 12th Economics Solutions Chapter 4 Consumption and Investment Functions

Question 3.
Explain the uses of multiplier?
Answer:
Uses of multiplier

Multiplier highlights the importance of investment in income and employment theory
The process throws light on the different stages of trade cycle.
It also helps in bringing the equality between S and I.
It helps in formulating Government policies.
It helps to reduce unemployment and achieve full employment.

Question 4.
Write the Accelerator Assumptions?
Answer:
Assumptions:

Absence of excess capacity in consumer goods industries.
Constant capital – output ratio
Increase in demand is assumed to be permanent
Supply of funds and other inputs is quite elastic
Capital goods are perfectly divisible in any required size.

Question 5.
Write the “Leverage Effect” and Equation Explanation?
Answer:
Leverage Effect:
The combined effect of the multiplier and the accelerator is also called the leverage effect which may lead the economy to very high or low level of income propagation.
Symbolically
Y = C + I_A + I_P
Y = Aggregate income
C = Consumption expenditure
T = autonomous investment; I_P = induced private investment

Part – D
Answer The Following Questions In One Page.

Question 1.
Briefly explain the Leakages of Multiplier?
Answer:
Leakages of multiplier:

The multiplier assumes that those who earn income are likely to spend a proportion of their additional income on consumption.
But in practice, people tend to spend their additional income on other items. Such expenses are known as leakages.

Payment towards past debts:
If a portion of the additional income is used for repayment of old loan, the MPC is reduced and as a result the value of multiplier is cut.

Purchase of existing wealth:

If income is used in purchase of existing wealth such as land, building and shares money is circulated among people and never enters into the consumption stream.
As a result the value of multiplier is affected.

Import of goods and services:

Income spent on imports of goods or services flows out of the country and has little chance to return to income stream in the country.
Thus imports reduce the value of multiplier.

Non availability of consumer goods:

The multiplier theory assumes instantaneous supply of consumer goods following demand.
But there is often a time lag.
During this gap (D > S) inflation is likely to rise.
This reduces the consumption expenditure and there by multiplier value.

Full employment situation:

Under conditions of full employment, resources are almost fully employed.
So, additional investment will lead to inflation only, rather than generation of additional real income.

Question 2.
Explain Marginal Propensity to Consume [MPC] and Multiplier with diagram and Diagrammatic explanation?
Answer:
Marginal propensity to consume and multiplier.
The propensity to consume refers to the portion of income spent on consumption.
The MPC refers to the relation between change in consumption (C) and change in income (Y).
Samacheer Kalvi 12th Economics Solutions Chapter 4 Consumption and Investment Functions
Symbolically MPC = ∆C/∆Y
The value of multiplier depends on MPC
Multiplier (K) = 1/1 – MPC
The multiplier is the reciprocal of one minus marginal propensity to consume.
Since marginal propensity to save is 1 – MPC. (MPC + MPS = 1).
Multiplier is 1/ MPS.
The multiplier is therefore defined as reciprocal of MPS.
Multiplier is inversely related to MPS and directly with MPC.
Numerically if MPC is 0.75, MPS is 0.25 and k is 4.
Using formula k = 1/1 – MPC
1/1 – 0.75 = 1/0.25 = 4
Taking the following values, we can explain the functioning of multiplier.
Samacheer Kalvi 12th Economics Solutions Chapter 4 Consumption and Investment Functions
C = 100 + 0.8 y; 1 = 100 1 = 10
Y = C + I
Y = 100 + 0.8y = 100 + (1000) = 900;
S = 100 = I
After I is raised by 10, now I = 110
Y = 100 + 0.8y + 110
0.2y = 210
Y = $\frac{210}{0.2}$ = 1050
Here C = 100 = 0.8 (1050) = 940; S = 110 = 1
Diagrammatic Explanation.
At 45° line y = C + S
It implies the variables in axis and axis are equal.
The MPC is assumed to be at 0.8 (C = 100 + 0.8y)
The aggregate demand (C + I) curve intersects 45° line at point E.
The original national income is 500.
(C = 100 + 0.8y = 100 + 0.8 (500) = 500)
When I is 100, y = 1000, C = 900;
S = 100 = I
The new aggregate demand curve is C+F = 100 + 0.8y + 100 + 10
Y = $\frac{210}{0.2}$ = 1050
C = 940; S = 110 = 1

Question 3.
Explain about Marginal Efficiency of Capital [MEC] short run factors and long run factors?
Answer:
(a) Short – Run Factors

1. Demand for the product:

If the market for a particular good is expected to grow and its costs are likely to fall, the rate of return from investment will be high.
If entrepreneurs expect a fall in demand for goods and a rise in cost, the investment will decline.

2. Liquid assets:

If the entrepreneurs are holding large volume of working capital, they can take advantage of the investment opportunities that come in their way.
The MEC will be high.

3. Sudden changes in income:

The MEC is also influenced by sudden changes in income of the entrepreneurs.
If the business community gets windfall profits, or tax concession the MEC will be high and hence investment in the country will go up.
On the other hand, MEC falls with the decrease in income.

4. Current rate of investment:

Another factor which influences MEC is the current rate of investment in a particular industry.
If in a particular industry, much investment has already taken place and the rate of investment currently going on in that industry is also very large, then the marginal efficiency of capital will be low.

5. Waves of optimism and pessimism:

The marginal efficiency of capital is also affected by waves of optimism and pessimism in the business cycle.
If businessmen are optimistic about future, the MEC will be likely to be high.
During periods of pessimism the MEC is under estimated and so will be low.

(b) Long – Run Factors
The long run factors which influence the marginal efficiency of capital are as follows:

1. Rate of growth of population:

Marginal efficiency of capital is also influenced by the rate of growth of population.
If population is growing at a rapid speed, it is usually believed that the demand of various types of goods will increase.
So a rapid rise in the growth of population will increase the marginal efficiency of capital and a slowing down in its rate of growth will discourage investment and thus reduce marginal efficiency of capital.

2. Technological progress:

If investment and technological development take place in the industry, the prospects of increase in the net yield brightens up.
For example, the development of automobiles in the 20th century has greatly stimulated the rubber industry, the steel and oil industry etc.
So we can say that inventions and technological improvements encourage investment in various projects and increase marginal efficiency of capital.

3. Monetary and Fiscal policies:
Cheap money policy and liberal tax policy pave the way for greater profit margin and so MEC is likely to be high.

4. Political environment:
Political stability, smooth administration, maintenance of law and order help to improve MEC.

5. Resource availability:
Cheap and abundant supply of natural resources, efficient labour and stock of capital enhance the MEC.

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Samacheer Kalvi 12th Economics Solutions Chapter 8 International Economic Organisations

April 24, 2024

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Tamilnadu Samacheer Kalvi 12th Economics Solutions Chapter 8 International Economic Organisations

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Samacheer Kalvi 12th Economics International Economic Organisations Text Book Back Questions and Answers

Part – A
Multiple Choice Questions.

Question 1.
International Monetary Fund was an outcome of …………………….
(a) Pandung Conference
(b) Dunkel Draft
(c) Bretton Woods Conference
(d) Doha Conference
Answer:
(c) Bretton Woods Conference

Question 2.
International Monetary Fund is having its headquarters at …………………….
(a) Washington D.C.
(b) New York
(c) Vienna
(d) Geneva
Answer:
(a) Washington D.C.

Question 3.
IBRD is otherwise called …………………….
(a) IMF
(b) World Bank
(c) ASEAN
(d) International Finance Corporation
Answer:
(b) World Bank

Question 4.
The other name for Special Drawing Rights is …………………….
(a) Paper gold
(b) Quotas
(c) Voluntary Export Restrictions
(d) None of these
Answer:
(a) Paper gold

Question 5.
The organization which provides long term loan is …………………….
(a) World Bank
(b) International Monetary Fund
(c) World Trade Organisation
(d) BRICS
Answer:
(a) World Bank

Question 6.
Which of the following countries is not a member of SAARC?
(a) Sri Lanka
(b) Japan
(c) Bangladesh
(d) Afghanistan
Answer:
(b) Japan

Question 7.
International Development Association is an affiliate of …………………….
(a) IMF
(b) World Bank
(c) SAARC
(d) ASEAN
Answer:
(b) World Bank

Question 8.
……………………. relates to patents, copyrights, trade secrets, etc.,
(a) TRIPS
(b) TRIMS
(c) GATS
(d) NAMA
Answer:
(a) TRIPS

Question 9.
The first ministerial meeting of WTO was held at …………………….
(a) Singapore
(b) Geneva
(c) Seattle
(d) Doha
Answer:
(a) Singapore

Question 10.
ASEAN meetings are held once in every ……………………. years.
(a) 2
(b) 3
(c) 4
(d) 5
Answer:
(b) 3

Question 11.
Which of the following is not the member of SAARC?
(a) Pakistan
(b) Sri Lanka
(c) Bhutan
(d) China
Answer:
(d) China

Question 12.
SAARC meets once in ……………………. years.
(a) 2
(b) 3
(c) 4
(d) 5
Answer:
(a) 2

Question 13.
The headquarters of ASEAN is …………………….
(a) Jaharta
(b) New Delhi
(c) Colombo
(d) Tokyo
Answer:
(a) Jaharta

Question 14.
The term BRIC was coined in …………………….
(a) 2001
(b) 2005
(c) 2008
(d) 2010
Answer:
(a) 2001

Question 15.
ASEAN was created in …………………….
(a) 1965
(b) 1967
(c) 1972
(d) 1997
Answer:
(b) 1967

Question 16.
The Tenth BRICS Summit was held in July 2018 at …………………….
(a) Beijing
(b) Moscow
(c) Johannesburg
(d) Brasilia
Answer:
(c) Johannesburg

Question 17.
New Development Bank is associated with …………………….
(a) BRICS
(b) WTO
(c) SAARC
(d) ASEAN
Answer:
(a) BRICS

Question 18.
Which of the following does not come under ‘Six dialogue partners’ of ASEAN?
(a) China
(b) Japan
(c) India
(d) North Korea
Answer:
(d) North Korea

Question 19.
SAARC Agricultural Information Centre (SAIC) works as a central information institution for agriculture related resources was founded on …………………….
(a) 1985
(b) 1988
(c) 1992
(d) 1998
Answer:
(b) 1988

Question 20.
BENELUX is a form of …………………….
(a) Free trade area
(b) Economic Union
(c) Common market
(d) Customs union
Answer:
(d) Customs union

Part – B
Answer The Following Questions.

Question 21.
Write the meaning of Special Drawing rights?
Answer:
Special Drawing Rights (SDRs):

The Fund has succeeded in establishing a scheme of Special Drawing Rights (SDRs) which is otherwise called ‘Paper Gold’.
They are a form of international reserves created by the IMF in 1969 to solve the problem of international liquidity.
They are allocated to the IMF members in proportion to their Fund quotas.
SDRs are used as a means of payment by Fund members to meet balance of payments deficits and their total reserve position with the Fund.
Thus SDRs act both as an international unit of account and a means of payment.
All transactions by the Fund in the form of loans and their repayments, its liquid reserves, its capital, etc., are expressed in the SDR.

Question 22.
Mention any two objectives of ASEAN?
Answer:

To accelerate the economic growth, social progress and cultural development in the region;
To promote regional peace and stability and adherence to the principles of the United Nations Charter.

Question 23.
Point out any two ways in which IBRD lends to member countries?
Answer:
The Bank advances loans to members in two ways

Loans out of its own fund,
Loans out of borrowed capital.

Question 24.
Define Common Market?
Answer:
Common market is established through trade pacts. A group formed by countries within a geographical area to promote duty free trade and free movement of labour and capital amongits members, e.g. European Common Market (ECM).

Question 25.
What is Free trade area?
Answer:

A free trade area is the region encompassing a trade bloc whose member countries have signed a free-trade agreement (FTA).
Such agreements involve cooperation between at least two countries to reduce trade barriers, e.g. SAFTA, EFTA.

Question 26.
When and where was SAARC Secretariat established?
Answer:
South Asian Association For Regional Co – Operation (SAARC):
1. The South Asian Association for Regional Co – operation (SAARC) is an organisation of South Asian nations, which was established on 8 December 1985 for the promotion of economic and social progress, cultural development within the South Asia region and also for friendship and co – operation with other developing countries.

2. The SAARC Group (SAARC) comprises of Bangaladesh, Bhutan, India, The Maldives, Nepal, Pakistan and Sri Lanka.

3. In April 2007, Afghanistan became its eighth member.

Question 27.
Specify any two affiliates of World Bank Group?
Answer:
Samacheer Kalvi 12th Economics Solutions Chapter 8 International Economic Organisations

Part – C
Answer The Following Questions.

Question 28.
Mention the various forms of economic integration?
Answer:
An economic union is composed of a common market with a customs union. The participant countries have both common policies on product regulation, freedom of movement of goods, services and the factors of production and a common external trade policy, (e.g. European Economic Union)
EU > CM > CU > FTA
EU – Economic Union >
CM – Common – Market >
CU – Customs Union >
FTA – Free Trade Area
The regional economic integration among the trade blocks such as SAARC (South Asian nations), ASEAN (South East Asia) and BRICS and their achievements.

Question 29.
What are trade blocks?
Answer:
1. Trade blocks cover different kinds of arrangements between or among countries for mutual benefit. Economic integration takes the form of Free Trade Area, Customs Union, Common Market and Economic Union.

2. A free trade area is the region encompassing a trade bloc whose member countries have signed a free-trade agreement (FTA). Such agreements involve cooperation between at least two countries to reduce trade barriers, e.g. SAFTA, EFTA.

3. A customs union is defined as a type of trade block which is composed of a free trade area with no tariff among members and (zero tariffs among members) with a common external tariff, e.g. BENELUX (Belgium, Netherland and Luxumbuarg).

4. Common market is established through trade pacts. A group formed by countries within a geographical area to promote duty free trade and free movement of labour and capital among its members, e.g. European Common Market (ECM).

5. An economic union is composed of a common market with a customs union. The participant countries have both common policies on product regulation, freedom of movement of goods, services and the factors of production and a common external trade policy. (e.g. European Economic Union).

Question 30.
Mention any three lending programmes of IMF?
Answer:
(I) Establishment of monetary reserve fund:

The Fund has played a major role in achieving the sizeable stock of the national currencies of different countries.
To meet the foreign exchange requirements of the member nations, IMF uses its stock to help the member nations to meet foreign exchange requirements.

(II) Monetary discipline and cooperation:

The IMF has shown keen interest in maintaining monetary discipline and cooperation among the member countries.
To achieve this objective, it has provided assistance only to those countries which make sincere efforts to solve their problems.

(III) Special interest in the problems of UDCs:

The notable success of the Fund is the maintenance of special interest in the acute problems of developing countries.
The Fund has provided financial assistance to solve the balance of payment problem of UDCs.
However, many UDCs continue to be UDCs, while the developed countries have achieved substantial growth.

Question 31.
What is Multilateral Agreement?
Answer:
1. Multilateral trade agreement:
It is a multi national legal or trade agreements between countries. It is an agreement between more than two countries but not many.

2. The various agreements implemented by the WTO such as TRIPS, TRIMS, GATS, AoA, MFA have been discussed.

Question 32.
Write the agenda of BRICS Summit, 2018?
Answer:

South Africa hosted the 10th BRICS summit in July 2018.
The agenda for BRICS summit 2018 includes Inclusive growth, Trade issues, Global governance, Shared Prosperity, International peace and security.

Question 33.
State briefly the functions of SAARC?
Answer:
Functions of SAARC:
The main functions of SAARC are as follows.

Maintenance of the co operation in the region
Prevention of common problems associated with the member nations.
Ensuring strong relationship among the member nations.
Removal of the poverty through various packages of programmes.
Prevention of terrorism in the region.

Question 34.
List out the achievements of ASEAN?
Answer:
The ASEAN Declaration states the aims and purposes of the Association as:

To accelerate the economic growth, social progress and cultural development in the region;
To promote regional peace and stability and adherence to the principles of the United Nations Charter;
To promote cooperation among the members of ASEAN through the exchange of knowledge and experience in the field of public sector auditing.
To provide a conducive environment and facilities for research, training, and education among the members
To serve as a centre of information and as an ASEAN link with other international organizations.

Part – D
Answer The Following Questions.

Question 35.
Explain the objectives of IMF?
Answer:
Objectives Of IMF:

To promote international monetary cooperation among the member nations.
To facilitate faster and balanced growth of international trade.
To ensure exchange rate stability by curbing competitive exchange depreciations.
To eliminate or reduce exchange controls imposed by member nations.
To establish multilateral trade and payment system in respect of current transactions instead of bilateral trade agreements.
To promote the flow of capital from developed to developing nations.
To solve the problem of international liquidity.

Question 36.
Bring out the functions of World Bank?
Answer:
Functions of IBRD (or) World Bank:
The World Bank performs the major role of providing loans for development works to member countries, especially to underdeveloped countries. The World Bank provides long¬term loans for various development projects. Article 1 of the Agreement states the functions performed by the world bank as follows.

(I) Investment for productive purposes:
The World Bank performs the function of assisting in the reconstruction and development of territories of member nations through facility of investment for productive purposes. It also encourages the development of productive facilities and resources in less developed countries.

(II) Balanced growth of international trade:
Promoting the long range balanced growth of trade at international level and the maintaining equilibrium in BOPs of member nations by encouraging international investment.

(III) Provision of loans and guarantees:
Arranging the loans or providing guarantees on loans by various other channels so as to execute important projects.

(IV) Promotion of foreign private investment:
The promotion of private foreign investment by means of guarantees on loans and other investment made by private investors. The Bank supplements private investment by providing finance for productive purpose out of its own resources or from borrowed funds.

(V) Technical services:
The World Bank facilitates different kinds of technical services to the member countries through Staff College and experts.

Question 37.
Discuss the role of WTO in India’s socio economic development?
Answer:
WTO and India:
India is the founding member of the WTO. India favours multilateral trade approach. It enjoys MFN status and allows the same status to all other trading partners. India benefited
from WTO on following grounds:

By reducing tariff rates on raw materials, components and capital goods, it was able to import more for meeting her developmental requirements. India’s imports go on increasing.
India gets market access in several countries without any bilateral trade agreements.
Advanced technology has been obtained at cheaper cost.
India is in a better position to get quick redressal from the trade disputes.
The Indian exporters benefited from wider market information.

Question 38.
Write a note on?
(a) SAARC
(b) BRICS.
Answer:
(a) South Asian Association For Regional Co – Operation (SAARC):

The South Asian Association for Regional Co – operation (SAARC) is an organisation of South Asian nations, which was established on 8 December 1985 for the promotion of economic and social progress, cultural development within the South Asia region and also for friendship and co-operation with other developing countries.
The SAARC Group (SAARC) comprises of Bangaladesh, Bhutan, India, The Maldives, Nepal, Pakistan and Sri Lanka.
In April 2007, Afghanistan became its eighth member.
The basic aim of the organisation is to accelerate the process of economic and social development of member states through joint action in the agreed areas of cooperation.
The SAARC Secretariat was established in Kathmandu (Nepal) on 16th January 1987.
The first SAARC summit was held at Dhaka in the year 1985.
SAARC meets once in two years. Recently, the 20th SAARC summit was hosted by Srilanka in 2018.

(b) BRICS:

BRICS is the acronym for an association of five major emerging national economies: Brazil, Russia, India, China and South Africa.
Since 2009, the BRICS nations have met annually at formal summits.
South Africa hosted the 10th BRICS summit in July 2018.
The agenda for BRICS summit 2018 includes Inclusive growth, Trade issues, Global governance, Shared Prosperity, International peace and security.
It’s headquarters is at Shanghai, China.
The New Development Bank (NDB) formerly referred to as the BRICS Development Bank was established by BRICS States.
The first BRICS summit was held at Moscow and South Africa hosted the Tenth Conference at Johanesberg in July 2018.
India had an opportunity of hosting fourth and Eighth summits in 2009 and 2016 respectively.
The BRICS countries make up 21 percent of global GDP. They have increased their share of global GDP threefold in the past 15 years.
The BRICS are home to 43 percent of the world’s population.
The BRICS countries have combined foreign reserves of an estimated $ 4.4 trillion

Samacheer Kalvi 12th Economics International Economic Organisations Addtional Questions and Answers

Part – A
I. Multiple Choice Questions.

1.
The IMF has ……………………. member countries with Republic.
(a) 169
(b) 179
(c) 189
(d) 199
Answer:
(c) 189

Question 2.
The Brettonwoods conference proposed IMF, World Bank and International Trade Organisation in …………………….
(a)1914
(b) 1924
(c) 1934
(d) 1944
Answer:
(d) 1944

Question 3.
The GATT was transformed into …………………….
(a) IMF
(b) World Bank
(c) WTO
(d) IDBI
Answer:
(c) WTO

Question 4.
International Monetary Fund headquarters are present in …………………….
(a) Geneva
(b) Washington DC
(c) England
(d) China
Answer:
(b) Washington DC

Question 5.
The IMF is maintaining exchange rate stability and emphasising …………………….
(a) valuvation
(b) Devaluevation
(c) Equilibrium
(d) Disequillibrium
Answer:
(b) Devaluevation

Question 6.
The buffer stock financing facility was started in …………………….
(a)1949
(b)1959
(c) 1969
(d) 1979
Answer:
(c) 1969

Question 7.
……………………. was setup to augment the availability to concessional resources to low Income countries.
(a) SAF
(b) IMF
(c) ESAF
(d) BSF
Answer:
(c) ESAF

Question 8.
Special Drawing called …………………….
(a) Gold
(b) Metal
(c) Paper Gold
(d) Gold Paper
Answer:
(c) Paper Gold

Question 9.
India has been beneficiaries of the major beneferciaries of the ……………………. fund.
(a) SDR
(b) ESAF
(c) IMF
(d) World Bank
Answer:
(c) IMF

Question 10.
IMF fund has provided finance assistance to solve the balance payment problems of …………………….
(a) SDR
(b) ESAF
(c) IMF
(d) World Bank
Answer:
(c) IMF

Question 11.
IBRD otherwise called the …………………….
(a) IMF
(b) SDR
(c) SAF
(d) World Bank
Answer:
(d) World Bank

Question 12.
IMF is a prerequisite to become a member of …………………….
(a) SDR
(b) SAF
(c) World Bank
(d) SAF
Answer:
(c) World Bank

Question 13.
……………………. was established to provide long term financial assistance to member countries.
(a) IMF
(b IBRD
(c) SAF
(d) ESAF
Answer:
(b IBRD

Question 14.
World Bank advances loans out of its own …………………….
(a) Fund
(b) Money
(c) Finance
(d) Credit
Answer:
(a) Fund

Question 15.
The IBRD has ……………………. member countries.
(a) 159
(b) 169
(c) 179
(d) 189
Answer:
(d) 189

Question 16.
World Bank’s membership has 151 countries in …………………….
(a) 1968
(b) 1978
(c) 1988
(d) 1998
Answer:
(c) 1988

Question 17.
……………………. grants loans to member countries only for productive purposes.
(a) IMF
(b) World bank
(c) SAF
(d) ESAF
Answer:
(b) World bank

Question 18.
……………………. the soft loan window of the bank provides loans to UDC at very low rate of interest.
(a) World Bank
(b) IDA
(c) IMF
(d) IBRD
Answer:
(b) IDA

Question 19.
……………………. was first suggested by India to the drafting committee.
(a) IBRD
(b) IDA
(c) IMF
(d) SAF
Answer:
(a) IBRD

Question 20.
India was the largest beneficiary of the ……………………. assistance.
(a) IBRD
(b) IDA
(c) IMF
(d) World bank
Answer:
(d) World bank

Question 21.
The WTO was established in 1995 as a 28 successor to the …………………….
(a) World Bank
(b) IDA
(c) GATT
(d) IFC
Answer:
(c) GATT

Question 22.
The first WTO conference was held at in ……………………. 1996.
(a) Argentia
(b) Kazakhstan
(c) Singapore
(d) America
Answer:
(c) Singapore

Question 23.
A result of ……………………. the dependence of LDCs on advanced countries for seeds, drugs, fertilizers and pesticides.
(a) TRIPS
(b) TRIMS
(c) GATS
(d) GATT
Answer:
(a) TRIPS

Question 24.
……………………. are related to conditions or restrictions in respect of foreign investment in the country.
(a) TRIPS
(b) TRIMs
(c) GATT
(d) GATS
Answer:
(b) TRIMs

Question 25.
……………………. is the first Multilateral set of rules covering trade in services like banking, insurance, transportation, communication, etc.
(a) TRIPS
(b) TRIMs
(c) GATT
(d) GATS
Answer:
(d) GATS

Question 26.
……………………. governed the world trade in textiles and garments since 1974.
(a) GATS
(b) GATT
(c) MFA
(d) TRIPS
Answer:
(c) MFA

Question 27.
Agriculture was included for the first time under …………………….
(a) GATS
(b) GATT
(c) MFA
(d) TRIMs
Answer:
(b) GATT

Question 28.
……………………. is the founding member of the WTO.
(a) India
(b) China
(c) Africa
(d) Russia
Answer:
(a) India

II. Match the following and choose the correct answer by using codes given below.

Question 1.
A. ITO – (i) 1945
B. IMF – (ii) 1944
C. WTO – (iii) 1945
D. World Bank – (iv) 1995
Codes:
(a) A (ii) B (iii) C (iv) D (i)
(b) A (i) B (ii) C (iii) D (iv)
(c) A (iii) B (iv) C (i) D (ii)
(d) A (iv) B (i) C (ii) D (iii)
Answer:
(a) A (ii) B (iii) C (iv) D (i)

Question 2.
A. International Monetary Fund – (i) Washington DC
B. World Trade Organisation – (ii) Washington DC
C. IBRD – (iii) 189 members
D. World Bank – (iv) Geneva
Codes:
(a) A(i) B (ii) C (iii) D (iv)
(b) A (ii) B (iii) C (iv) D (i)
(c) A (iii) B (iv) C (iv) D (ii)
(d) A (iv) B (i) C (ii) D (iii)
Answer:
(c) A (iii) B (iv) C (iv) D (ii)

Question 3.
A. SDR – (i) 1963
B. CFF – (ii) Paper Gold
C. BSF – (iii) 1986
D. SAF – (iv) 1969
Codes:
(a) A (iii) B (ii) C(i) D (iv)
(b) A (ii) B (i) C (iv) D (iii)
(c) A (i) B (iv) C (iii) D (ii)
(d) A (iv) B (iii) C (ii) D (i)
Answer:
(b) A (ii) B (i) C (iv) D (iii)

Question 4.
A. SAF – (i) Structural Adjustment Facility
B. BSF – (ii) Special Drawing Rights
C. CFF – (iii) Buffer Stock Facility
D. SDR – (iv) Compensatory Financing Facility
Codes:
(a) A (i) B (iii) C (iv) D (ii)
(b) A (ii) B (iv) C (iii) D (i)
(c) A (iii) B (ii) C(i) D (iv)
(d) A (iv) B (i) C (ii) D (iii)
Answer:
(a) A (i) B (iii) C (iv) D (ii)

Question 5.
A. IDA – (i) Multilateral Investment Guarantee Agency
B. IFC – (ii) International Development Association
C. MIGA – (iii) International Centre for Settlement of Investment Disputes
D. ICSID – (iv) International Finance Corporation
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (iii) B (i) C (iv) D (ii)
(c) A (ii) B (iv) C (i) D (iii)
(d) A (iv) B (iii) C (ii) D (i)
Answer:
(c) A (ii) B (iv) C (i) D (iii)

III. State whether the statements are true or false.

Question 1.
(i) Functions of IBRD is called
(a) Investment for productive purposes
(b) Provision of loans and guarantees.
(ii) Functions of IBRD is called
(a) Balanced growth of International trade
(b) Promotion of foreign private investment.
(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 2.
Objectives of WTO are
(i) To ensure reduction of tariff and other barriers.
(ii) Low level of standard of living.
(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(c) (i) is true but (ii) is false

Question 3.
(i) GATS is the first multilateral set of rules covering trade in services like Banking, Insurance, Transportation, Communication, etc.
(ii) GATS are related to conditions or restrictions in respect of Foreign Investment.
(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(c) (i) is true but (ii) is false

Question 4.
Major objectives of SAARC
(i) To accelerate economic growth, social progress and cultural development in the region.
(ii) To promote and strengthen collective self – reliance among the countries of South Asia.
(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 5.
Major Functions of the ASEAN
(i) It fosters co – operations in many areas including agriculture.
(ii) It paves way for market and investment opportunities for the all nations.
(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(b) Both (i) and (ii) are false

IV. Which is the following is correctly matched.

Question 1.
(a) ITO – 1944
(b) World bank – 1946
(c) WTO – 1947
(d) IMF – 1995
Answer:
(a) ITO – 1944

Question 2.
(a) World Trade Organisation – Africa
(b) World Bank – Geneva
(c) International Monetary Fund – Washington DC
(d) GATT – Australia
Answer:
(c) International Monetary Fund – Washington DC

Question 3.
(a) Objectives of IMF – To promote textiles
(b) Functions of IMF – Exchange stability
(c) Facilities offered by IMF – Basic Debit Facility
(d) Achievements of IMF – Country discipline and co-operation
Answer:
(b) Functions of IMF – Exchange stability

Question 4.
(a) World Bank’s procedure – Loans out of its own fund
(b) Functions of IBRD – Promotion of government investment
(c) World Bank – Grants loans for Industry
(d) IDA – High interest of the loan
Answer:
(c) World Bank – Grants loans for Industry

Question 5.
(a) WTC headquarter – Newyork – USA
(b) WTO conference held at – Australia
(c) WTO Secretary General – Kazakhstan
(d) GATS service like – Industries
Answer:
(a) WTC headquarter – Newyork – USA

V. Which is the following is not correctly matched.

Question 1.
(a) MFA agreement – Textiles and garments
(b) WTO achievements – BOP problems has declined
(c) TRIPS – The dependence of LDCs on advanced countries for seeds, fertilizers, drugs has increased
(d) AOA – Trade development
Answer:
(d) AOA – Trade development

Question 2.
(a) Head quarters of SAARC – Kathmandu
(b) Member countries of IMF – 189
(c) World Trade Organisation – Geneva
(d) Long term loan – SAARC
Answer:
(d) Long term loan – SAARC

Question 3.
(a) GATT – WTO
(.b) SDR – 1969
(c) ITO – 1944
(d) SAARC – Investment
Answer:
(d) SAARC – Investment

Question 4.
(a) ASEAN – Bangkok
(b) IFC – 1996
(c) BRICS – 2001
(d) WTO conference – Singapore in 1996
Answer:
(b) IFC – 1996

Question 5.
(a) World Bank – 1945
(b) IFC – World Bank Group
(c) IBRD – World Bank
(d) SDRs – Monetary
Answer:
(d) SDRs – Monetary

VI. Pick the odd one out.

Question 1.
Objectives of WTO
(a) To ensure reduction of tariff and other barriers
(b) To eliminate discrimination in trade
(c) To facilitate low standard of living
(d) To facilitate optimal use of world’s resources
Answer:
(c) To facilitate low standard of living

Question 2.
WTO Agreements
(a) TRIPs
(b) TRIMs
(c) GAS
(d) GATS
Answer:
(c) GAS

Question 3.
Trade Blocks
(a) A free trade area
(b) A custom union
(c) Big market
(d) An economic union
Answer:
(c) Big market

Question 4.
ASEAN member countries
(a) Indonesia
(b) Malaysia
(c) Philippines
(d) America
Answer:
(d) America

Question 5.
Objectives of BRICs
(a) To increase trade co-operation by making an exclusive trade block
(b) To increase regional co-operation
(c) This group of nations is expecially meant for North-North frame work for co-operation
(d) To create a seperate trade block made for developing countries for trade co-operation
Answer:
(c) This group of nations is expecially meant for North-North frame work for co-operation

VII. Assertion and Reason.

Question 1.
Assertion (A): BRICS is the acronym for an association of five major emerging national economies Brazil, Russia, India, China and South Africa.
Reason (R): Originally the first four were grouped as “BRIC” before the Induction of South Africa in 2010.
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’

Question 2.
Assertion (A): SAARC is promote the welfare of the people of South Asia and improve their quality of life.
Reason (R): To strengthen co-operation with other under developing countries.
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(c) ‘A’ is true but ‘R’ is false

Question 3.
Assertion (A): TRIMs are related to conditions or restrictions in respect of foreign investment in the country.
Reason (R): TRIMs calls for introducing equal treatment for Indian companies.
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(c) ‘A’ is true but ‘R’ is false

Question 4.
Assertion (A): WTO are to ensure reduction of tariff and other barriers.
Reason (R): WTO are standard of living is very low.
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(c) ‘A’ is true but ‘R’ is false

Question 5.
Assertion (A): The Dunkel Draft, formulated by Arthur Dunkel, its Secretary General became the base for WTO.
Reason (R): The first WTO conference was held at Singapore in 1996.
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’

Question 6.
Assertion (A): IMF objectives are facilitate faster and balanced growth of Internal trade.
Reason (R): IMF objectives are to promote international monetary co-operation among the member nations.
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false
(d) ‘A’ is false but ‘R’ is true
Answer:
(d) ‘A’ is false but ‘R’ is true

Part – B
Answer The Following Questions In One or Two Sentences.

Question 1.
Write IMF Functions group?
Answer:
The functions of the IMF are grouped under three heads.

Financial – Assistance to correct short and medium tenn deficit in BOP;
Regulatory – Code of conduct and
Consultative – Counseling and technical consultancy.

Question 2.
Define IBRD?
Answer:

The International Bank for Reconstruction and Development (IBRD), otherwise called the World Bank (WB) was established in 1945 under the Bretton Woods Conference in 1944.
The purpose is to bring about a smooth transition from a war-time to peace-time economy.
It is known as a sister institution along with the International Monetary Fund.
The membership in International Monetary Fund is a prerequisite to become a member of IBRD.
The IBRD was established to provide long term financial assistance to member countries.

Question 3.
Write the World bank activities of Rural areas?
Answer:
The bank now also takes interest in the activities of the development of rural areas such as:

Spread of education among the rural people
Development of roads in rural areas and
Electrification of the villages.

Question 4.
Define World Trade Centre?
Answer:

The WTO was established in 1995 as a successor to the GATT.
It is a new international organization set up as a permanent body and is designed to play the role of watch dog in the spheres of trade in goods and services, foreign investment and intellectual property rights.
The Dunkel Draft, formulated by Arthur Dunkel, its Secretary General became the base for WTO.

Question 5.
Define World Trade Organisation?
Answer:

WTC headquarters located at New York, USA.
It featured the landmark Twin Towers which was established on 4th April 1973.
Later it was destroyed on 11th September 2001 by the craft attack.
It brings together businesses involved in international trade from around the globe.

Question 6.
What is meaning of SAPTA, SAIC, SADF?
Answer:

SAARC Preferential Trading Agreement (SAPTA)
SAARC Agricultural Information Centre (SAIC)
South Asian Development Fund (SADF)

Question 7.
Write the ‘ASEAN’ member of countries?
Answer:
ASEAN was established on 8 August 1967 in Bangkok by the five original member countries: Indonesia, Malaysia, Philippines, Singapore and Thailand.

Question 8.
Who are “dialogue partners”?
Answer:
The ASEAN, there are six “dialogue partners” which have been participating in its deliberations. They are China, Japan, India, South Korea, New Zealand and Australia.

Part – C
Answer The Following Questions In One Paragraph.

Question 1.
Brief notes on India and IMF?
Answer:
India and IMF:
1. Till 1970, India stood fifth in the Fund and it had the power to appoint a permanent Executive Director.

2. India has been one of the major beneficiaries of the Fund assistance.

3. It has been getting aid from the various Fund Agencies from time to time and has been regularly repaying its debt.

4. India’s current quota in the IMF is SDRs (Special Drawing Rights) 5,821.5 million, making it the 13th largest quota holding country at IMF with shareholdings of 2.44%.

5. Besides receiving loans to meet deficit in its balance of payments, India has benefited in certain other respects from the membership of the Fund.

Question 2.
Write the objectives of World Bank?
Answer:
The following are the objectives of the World Bank:

To help member countries for economic reconstruction and development.
To stimulate long-run capital investment for restoring Balance of Payments (BoP) equilibrium and thereby ensure balanced development of international trade among the member nations.
To provide guarantees for loans meant for infrastructural and industrial projects of member nations.
To help war ravaged economies transform into peace economies.
To supplement foreign private investment by direct loans out of its own funds for productive purposes.

Question 3.
Explain the objectives of WTO?
Answer:

To ensure reduction of tariff and other barriers.
To eliminate discrimination in trade.
To facilitate higher standard of living.
To facilitate optimal use of world’s resources.
To enable the LDCs to secure fair share in the growth of international trade.
To ensure linkages between trade policies, environmental policies and sustainable development.

Question 4.
Write the TRIPs agreement?
Answer:
Agreement on Trade Related Intellectual Property Rights (TRIPs):
1. Intellectual Property Rights include copy right, trade marks, patents, geographical indications, trade secrets, industrial designs, etc.

2. TRIPS Agreement provides for granting product patents instead of process patents.

3. The period of protection will be 20 years for patents, 50 years for copy rights, 7 years for trade marks and 10 years for layout designs.

4. As a result of TRIPS, the dependence of LDCs on advanced countries for seeds, drugs, fertilizers and pesticides has increased.

5. Farmers are depending on the industrial firm for their seeds.

Question 5.
Explain the functions of WTO?
Answer:
The following are the functions of the WTO
1. It facilitates the implementation, administration and operation of the objectives of the Agreement and of the Multilateral Trade Agreements.

2. It provides the forum for negotiations among its members, concerning their multilateral trade relations in matters relating to the agreements.

3. It administers the Understanding on Rules and Procedures governing the Settlement of Disputes.

4. It cooperates with the IMF and the World Bank and its affiliated agencies with a view to achieving greater coherence in global economic policy making.

Question 6.
Explain the functions of ASEAN?
Answer:
Functions of the ASEAN:
1. It facilitates free movement of goods, services and investments within ASEAN by creating a single regional market like the European Union.

2. It provides free access to the marketers of one member country to the markets of all other member countries, thus fostering growth in the region.

3. It improves business competitiveness between businesses from different countries and also narrow developmental gaps between member countries.

4. It paves way for market and investment opportunities for the member nations.

5. It fosters co – operations in many areas including industry and trade.
All the ASEAN economies experienced a great economic crisis in the year 1997.

Question 7.
Explain the major achievements of WTO?
Answer:
The major achievements of WTO are as follows
1. Use of restrictive measures for BoP problems has declined markedly;

2. Services trade has been brought into the multilateral system and many countries, as in goods, are opening their markets for trade and investment;

3. The trade policy review mechanism has created a process of continuous monitoring of trade policy developments.

Part – D
Answer The Following Questions In About A Page.

Question 1.
Explain the IMF functions?
Answer:
Functions of IMF:
(I) Bringing stability in exchange rate:
The IMF is maintaining exchange rate stability and emphasising devaluation criteria, restricting members to go in for multiple exchange rates and also to buy or sell gold at prices other than declared par value. .

(II) Correcting BOP Disequilibrium:
The IMF is helping the member countries in eliminating or minimizing the short-period disequilibrium in their balance of payments either by selling or lending foreign currencies to the member nation.

Samacheer Kalvi 12th Economics Solutions Chapter 8 International Economic Organisations

(III) Determining par values:
1. IMF enforces the system of determination of par values of the currencies of the member countries.

2. According to the Articles of Agreement of the IMF, every member nation should declare the par value of its currency in terms of gold or US dollars.

3. Under this article, IMF ensures smooth working of the international monetary system, in favour of some developed countries.

(IV) Balancing demand and supply of currencies:
1. IMF is entrusted with the important function of maintaining balance between demand and supply of various currencies.

2. The Fund (IMF) can declare a currency as scarce currency which is in great demand and can increase its supply by borrowing it from the country concerned or by purchasing the same currency in exchange of gold.

(V) Reducing trade restrictions:
The Fund also aims at reducing tariffs and other trade barriers imposed by the member countries with the purpose of removing restrictions on remittance of funds or to avoid discriminating practices.

(VI) Providing credit facilities:
1. IMF is providing different borrowing and credit facilities with the objective of helping the member countries.

2. These credit facilities offered by it include basic credit facility, extended fund facility for a period of three years, compensatory financing facility and structural adjustment facility.

Question 2.
Briefly explain facilities offered by IMF?
Answer:
Facilities offered by IMF:
The Fund has created several new credit facilities for its members. Chief among them are:

(I) Basic Credit Facility:

The IMF provides financial assistance to its member nations to overcome their temporary difficulties relating to balance of payments.
A member nation can purchase from the Fund other currencies or SDRs, in exchange for its own currency, to finance payment deficits.
The loan is repaid when the member repurchases its own currency with other currencies or SDRs.
A member can unconditionally borrow from the Fund in a year equal to 25% of its quota.
This unconditional borrowing right is called the reserve tranche.

(II) Extended Fund Facility:

Under this arrangement, the IMF provides additional borrowing facility up to 140% of the member’s quota, over and above the basic credit facility.
The extended facility is limited for a period up to 3 years and the rate of interest is low.

(III) Compensatory Financing Facility:

In 1963, IMF established compensatory financing facility to provide additional financial assistance to the member countries, particularly primary producing countries facing shortfall in export earnings.
In 1981, the coverage of the compensatory financing facility was extended to payment problem caused by the fluctuations in the cost of cereal inputs.

(IV) Buffer Stock Facility:

The buffer stock financing facility was started in 1969.
The purpose of this scheme was to help the primary goods (food grains) producing countries to finance contributions to buffer stock arrangements for the stabilisation of primary product prices.

(V) Supplementary Financing Facility:
Under the supplementary financing facility, the IMF makes temporary arrangements to provide supplementary financial assistance to member countries facing payments problems relating to their present quota sizes.

(VI) Structural Adjustment Facility:
1. The IMF established Structural Adjustment Facility (SAF) in March 1986 to provide additional balance of payments assistance on concessional terms to the poorer member countries.

2. In December 1987, the Enhanced Structural Adjustment Facility (ESAF) was set up to augment the availability of concessional resources to low income countries.

3. The purpose of SAF and ESAF is to force the poor countries to undertake strong macroeconomic and structural programmes to improve their balance of payments positions and promote economic growth.

Question 3.
Explain the achievements of World Bank?
Answer:
Achievements of World Bank:
The World Bank is said to be successful in achieving its primary objective of reconstruction and development of war ravaged nations. It helped greatly in the reconstruction of Europe after the World War II. It has been providing the developed and developing countries the same treatment in the process of growth.

(I) It is noted that the Bank’s membership has increased from the initial number of 30 countries to 68 countries in 1960 and to 151 countries in 1988. The IBRD has 189 member countries,

(II) The Bank grants medium and long-term loans (i.e., payable over a period of 15-20 years) for reconstruction and development purposes to the member countries. The actual term of a loan depends upon the estimated useful life of the equipment or plant financed.

(III) Initially the World Bank’s loans were mainly directed at the European countries for financing their programmes of reconstruction. Later it changed its development loan strategy and lays more emphasis of financing schemes for the poor masses of the developing countries.

(IV) The World Bank grants loans to member countries only for productive purposes particularly for agriculture, irrigation, power and transport. In other words, the Bank strengthens infrastructure needed for further development.

(V) The International Development Association (IDA), the Soft Loan Window of the Bank provides loans to UDCs at very low rate of interest. However, the economic inequality among the member-countries goes on increasing. Many African countries are yet to improve their economic status.

Question 4.
Bringout the objectives of SAARC?
Answer:
Objectives of SAARC:
According to Article I of the Charter of the SAARC, the objectives of the Association are as follows:

To promote the welfare of the people of South Asia and improve their quality of life
To accelerate economic growth, social progress and cultural development in the region
To promote and strengthen collective self – reliance among the countries of South Asia
To contribute to mutual trust, understanding and appreciation of one another’s problems
To promote active collaboration and mutual assistance in the economic, social, cultural, technical and scientific fields
To strengthen co – operation with other developing countries
To strengthen cooperation among themselves in international forums on matters of common interest
To cooperate with international and regional organisations with similar aims and purposes.

Question 5.
Briefly explain achievements of SAARC?
Answer:
Achievements of SAARC:
1. The establishment of SAARC Preferential Trading Agreement (SAPTA) and reduction in tariff and non-tariff barriers on imports.

2. The setting up of Technical Committees for economic cooperation among SAARC countries relating to agriculture, communications, education, health and population, rural development, science and technology, tourism, etc.

3. SAARC has established a three-tier mechanism for exchanging information on poverty reduction programmes which is passed on to member countries.

4. SAARC Agricultural Information Centre (SAIC) in 1988 works as a central information institution for agriculture related resources like fisheries, forestry, etc.

5. South Asian Development Fund (SADF) for development projects, human resource development and infrastructural development projects. With all these tall claims, the inter- SAARC Trade has not gone beyond three percent in the last 30 years.

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Samacheer Kalvi 12th Economics Solutions Chapter 2 National Income

April 24, 2024

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Tamilnadu Samacheer Kalvi 12th Economics Solutions Chapter 2 National Income

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Samacheer Kalvi 12th Economics National Income Text Book Back Questions and Answers

Part – A

Multiple Choice Questions.

Question 1.
Net National product at factor cost is also known as –
(a) National Income
(b) Domestic Income
(c) Per capita Income
(d) Salary
Answer:
(a) National Income

Question 2.
Primary sector is –
(a) Industry
(b) Trade
(c) Agriculture
(d) Construction
Answer:
(c) Agriculture

Question 3.
National income is measured by using ………………. methods.
(a) Two
(b) Three
(c) Five
(d) Four
Answer:
(b) Three

Question 4.
Income method is measured by summing up of all forms of –
(a) Revenue
(b) Taxes
(c) Expenditure
(d) Income
Answer:
(d) Income

Question 5.
Which is the largest figure?
(a) Disposable income
(b) Personal Income
(c) NNP
(d) GNP
Answer:
(d) GNP

Question 6.
Expenditure method is used to estimate national income in –
(a) Construction sector
(b) Agricultural Sector
(c) Service sector
(d) Banking sector
Answer:
(a) Construction sector

Question 7.
Tertiary sector is also called as ……………………….. sector.
(a) Service
(b) Income
(c) Industrial
(d) Production
Answer:
(a) Service

Question 8.
National income is a measure of the performance of an economy.
(a) Industrial
(b) Agricultural
(c) Economic
(d) Consumption
Answer:
(c) Economic

Question 9.
Per capita income is obtained by dividing the National income by –
(a) Production
(b) Population of a country
(c) Expenditure
(d) GNP
Answer:
(b) Population of a country

Question 10.
GNP = ……………………… + Net factor income from abroad.
(a) NNP
(b) NDP
(c) GDP
(d) Personal income
Answer:
(c) GDP

Question 11.
NNP stands for ………………………
(a) Net National Product
(b) National Net product
(c) National Net Provident
(d) Net National Provident
Answer:
(a) Net National Product

Question 12.
…………………… is deducted from gross value to get the net value.
(a) Income
(b) Depreciation
(c) Expenditure
(d) Value of final goods
Answer:
(b) Depreciation

Question 13.
The financial year in India is –
(a) April 1 to March 31
(b) March 1 to April 30
(c) March 1 to March 16
(d) January 1 to December 31
Answer:
(a) April 1 to March 31

Question 14.
When net factor income from abroad is deducted from NNP, the net value is –
(a) Gross National Product
(b) Disposable Income
(c) Net Domestic Product
(d) Personal Income
Answer:
(c) Net Domestic Product

Question 15.
The value of NNP at production point is called –
(a) NNP at factor cost
(b) NNP at market cost
(c) GNP at factor cost
(d) Per capita income
Answer:
(a) NNP at factor cost

Question 16.
The average income of the country is –
(a) Personal Income
(b) Per capita income
(c) Inflation Rate
(d) Disposal Income
Answer:
(b) Per capita income

Question 17.
The value of national income adjusted for inflation is called –
(a) Inflation Rate
(b) Disposal Income
(c) GNP
(d) Real national income
Answer:
(d) Real national income

Question 18.
Which is a flow concept?
(a) Number of shirts
(b) Total wealth
(c) Monthly income
(d) Money supply
Answer:
(c) Monthly income

Question 19.
PQLI is the indicator of –
(a) Economic growth
(b) Economic welfare
(c) Economic progress
(d) Economic development
Answer:
(b) Economic welfare

Question 20.
The largest proportion of national income comes from –
(a) Private sector
(b) Local sector
(c) Public sector
(d) None of the above
Answer:
(a) Private sector

Part – B
Answer The Following Questions In One or Two Sentences.

Question 21.
Define National Income?
Answer:
National Income means the total money value of all final goods and services produced in a country during a particular period of time (one year).

Question 22.
Write the formula for calculating GNP?
Answer:
GNP at market prices means the gross value of final goods and services produced annually in a country plus net factor income from abroad
(C + I + G + (X – M) + (R – P)).

Question 23.
What is the difference between NNP and NDP?
Answer:
NNP:

NNP refers to the market value of output.
NNP at factor cost is the total of income payment made to factors of production.

NDP:

NDP is the value of net output of the economy during the year
The country’s capital equipment wears out of becomes outdated each year during the production process.

Question 24.
Trace the relationship between GNP and NNP?
Answer:
GNP:
1. Total money value of final goods and services produced in a country during a particular year (one year).

NNP:
1. Total money value of final goos and services produced in a country in a country during a particular year (one year).

Question 25.
What do you mean by the term ‘Personal Income’?
Answer:
Personal income is the total income received by the individuals of a country from all sources before payment of direct taxes in a year.

Question 26.
Define GDP deflator?
Answer:
GDP is the total market value of final goods and services produced within the country during a year. This is calculated at market prices and is known as GDP at market prices. Thus GDP by expenditure method at market prices = C + I + G + (X – M)
Where C – consumption goods;
I – Investment goods;
G – Government purchases;
(X – M) is net export which can be positive or negative.

Question 27.
Why is self consumption difficult in measuring national income?
Answer:

Farmers keep a large portion of food and other goods produced on the farm for self consumption.
The problem is whether that part of the produce which is not sold in the market can be included in national income or not.

Part – C
Answer The Following Questions In One Paragraph.

Question 28.
Write a short note on per capita income?
Answer:
Per Capita Income:

The average income of a person of a country in a particular year is called Per Capita Income.
Per capita income is obtained by dividing national income by population.

Question 29.
Differentiate between personal and disposable income?
Answer:
Personal income:
Personal income is the total income received by the individuals of a country from all sources before payment of direct taxes in a year.

Disposable income:
Disposable Income is also known as Disposable personal income. It is the individuals income after the payment of income tax. This is the amount available for households for consumption.

Question 30.
Explain briefly NNP at factor cost?
Answer:
Net National Product refers to the value of the net output of the economy during the year. NNP is obtained by deducting the value of depreciation, or replacement allowance of the capital assets from the GNP. It is expressed as, NNP = GNP – depreciation allowance.

Question 31.
Give short note on Expenditure method?
The Expenditure Method (Outlay method):
Answer:

The total expenditure incurred by the society in a particular year is added together.
To calculate the expenditure of a society, it includes personal consumption expenditure, net domestic investment, government expenditure on consumption as well as capital goods and net exports.

Question 32.
What is the solution to the problem of double counting in the estimation of national income?
Answer:

The value obtained is actually the GNP at market prices. Care must be taken to avoid double counting.
The value of the final product is derived by the summation of all the values added in the productive process.
To avoid double counting, either the value of the final output should be taken into the estimate of GNP or the sum of values added should be taken.
Double counting is to be avoided under value added method.
Any commodity which is either raw material or intermediate good for the final production should not be included.
For example, value of cotton enters value of yam as cost, and value of yam in cloth and
that of cloth in garments.
At every stage value added only should be calculated.

Question 33.
Write briefly about national income and welfare?
Answer:
National Income and Welfare:
National Income is considered as an indicator of the economic wellbeing of a country. The per capita income as an index of economic welfare suffers from limitations which are stated below:

The economic welfare depends upon the composition of goods and services provided. The greater the proportion of capital goods over consumer goods, the improvement in economic welfare will be lesser.
Higher GDP with greater environmental hazards such as air, water and soil pollution will be little economic welfare.
The production of war goods will show the increase in national output but not welfare.
An increase in per capita income may be due to employment of women and children or forcing workers to work for long hours. But it will not promote economic welfare.

Question 34.
List out the uses of national income?
Answer:
The following are some of the concepts used in measuring national income?
GDP:

GDP is the total market value of final goods and services produced within the country during a year.
This is calculated at market prices and is known as GDP at market prices. Thus GDP by expenditure method at market

prices = C + I + G + (X-M)
Where C – Consumption goods;
I – Investment goods;
G – Government purchases;
(X – M) is net export which can be positive or negative.

Net National Product (NNP) (at Market price):

Net National Product refers to the value of the net output of the economy during the year.
NNP is obtained by deducting the value of depreciation, or replacement allowance of the capital assets from the GNP. It is expressed as,
NNP = GNP – depreciation allowance.

NNP at Factor cost:

NNP refers to the market value of output.
NNP at factor cost is the total of income payment made to factors of production.

Personal Income:

Personal income is the total income received by the individuals of a country’ from all sources before payment of direct taxes in a year.

Per Capita Income:

The average income of a person of a country in a particular year is called Per Capita Income.
Per capita income is obtained by dividing national income by population.

Disposable Income:

Disposable Income is also known as Disposable personal income.
It is the individuals income after the payment of income tax.
This is the amount available for households for consumption.

Real Income:

Nominal income is national income expressed in terms of a general price level of a particular year in other words, real income is the buying power of nominal income.

GDP deflator:

GDP deflator is an index of price changes of goods and services included in GDP.
It is a price index which is calculated by dividing the nominal GDP in a given year by the real GDP for the same year and multiplying it by 100.

Part – D
Answer The Following Questions In One Page.

Question 35.
Explain the importance of national income
Importance of National Income Analysis
Answer:
National income is of great importance for the economy of a country. Nowadays the national income is regarded as accounts of the economy, which are known as social accounts. It enables us:
1. To know the relative importance of the various sectors of the economy and their contribution towards national income; from the calculation of national income, we could find how income is produced, how it is distributed, how much is spent, saved or taxed.

2. To formulate the national policies such as monetary policy, fiscal policy and other policies; the proper measures can be adopted to bring the economy to the right path with the help of collecting national income data.

3. To formulate planning and evaluate plan progress; it is essential that the data pertaining to a country’s gross income, output, saving and consumption from different sources should be available for economic planning.

4. To build economic models both in short – run and long – run.

5. To make international comparison, inter – regional comparison and inter – temporal comparison of growth of the economy during different periods.

6. To know a country’s per capita income which reflects the economic welfare of the country (Provided income is equally distributed)

7. To know the distribution of income for various factors of production in the country.

8. To arrive at many macro economic variables namely, Tax – GDP ratio, Current Account Deficit – GDP ratio, Fiscal Deficit – GDP ratio, Debt – GDP ratio etc.

Question 36.
Discuss the various methods of estimating the national income of a country?
Answer:
There are three methods that are used to measure national income.

Production or value added method
Income method or factor earning method
Expenditure method

And if these methods are done correctly, the following equation must hold
Output = Income = Expenditure
This is because the three methods are circular in nature. It begins as production, through recruitments of factors of production, generating income and going as incomes to factors of production.

Product Method:
Product method measures the output of the country. It is also called inventory method. Under this method, the gross value of output from different sectors like agriculture, industry, trade and commerce, etc., is obtained for the entire economy during a year. The value obtained is actually the GNP at market prices. Care must be taken to avoid double counting.

Income Method (Factor Earning Method):
This method approaches national income from the distribution side. Under this method, national income is calculated by adding up all the incomes generated in the course of producing national product.
National income is calculated as domestic factor income plus net factor incomes from abroad. In short,
Y = w + r + i + π + (R – P)
w = wages, r = rent, i = interest, n = profits,
This method is adopted for estimating the contributions of the remaining sectors, viz., small enterprises, banking and insurance, commerce and transport, professions, liberal arts and domestic service, public authorities, house property and foreign sector transaction.

The Expenditure Method (Outlay method): \
The total expenditure incurred by the society in a particular year is added together. To calculate the expenditure of a society, it includes personal consumption expenditure, net domestic investment, government expenditure on • consumption as well as capital goods and net exports. Symbolically,
GNP = C + I + G + (X – M)
C – Private consumption expenditure
I – Private Investment Expenditure
G – Government expenditure
X – M = Net exports

Question 37.
What are the difficulties involved in the measurement of national income?
Answer:
Difficulties in Measuring National Income:

In India, a special conceptual problem is posed by the existence of a large, unorganised and non-monetised subsistence sector where the barter system still prevails for transacting goods and services.
Here, a proper valuation of output is very difficult.

Transfer payments:

Government makes payments in the form of pensions, unemployment allowance, subsidies, etc. These are government expenditure.
But they are not included in the national income.
Because they are paid without adding anything to the production processes.
During a year, Interest on national debt is also considered transfer payments because it is paid by the government to individuals and firms on their past savings without any productive work.

Difficulties in assessing depreciation allowance:

The deduction of depreciation allowances, accidental damages, repair and replacement charges from the national income is not an easy task.
It requires high degree of judgment to assess the depreciation allowance and other charges.
Unpaid services:
A housewife renders a number of useful services like preparation of meals, serving, tailoring, mending, washing, cleaning, bringing up children, etc.
She is not paid for them and her services are not directly included in national income.

Income from illegal activities:

Income earned through illegal activities like gambling, smuggling, illicit extraction of liquor, etc., is not included in national income.
Such activities have value and satisfy the wants of the people but they are not considered as productive from the point of view of society.

Production for self-consumption and changing price:

Farmers keep a large portion of food and other goods produced on the farm for self consumption.
The problem is whether that part of the produce which is not sold in the market can be included in national income or not.

Capital Gains:

The problem also arises with regard to capital gains.
Capital gains arise when a capital asset such as a house, other property, stocks or shares, etc. is sold at higher price than was paid for it at the time of purchase.
Capital gains are excluded from national income.

Statistical problems:

There are statistical problems, too. Great care is required to avoid double counting. Statistical data may not be perfectly reliable, when they are compiled from numerous sources.
Skill and efficiency of the statistical staff and cooperation of people at large are also equally important in estimating national income.

Question 38.
Discuss the importance of social accounting in economic analysis?
Answer:
National Income and Social Accounting:

National income is also being measured by the social accounting method.
Under this method, the transactions among various sectors such as firms, households, government, etc., are recorded and their interrelationships traced.
The social accounting framework is useful for economists as well as policy makers, because it represents the major economic flows and statistical relationships among various sectors of the economic system.
It becomes possible to forecast the trends of economy more accurately.

Social Accounting and Sector:

Under this method, the economy is divided into several sectors.
A sector is a group of individuals or institutions having common interrelated economic transactions.
The economy is divided into the following sectors:
1. Firms
2. Households
3. Government
4. Rest of the world and
5. Capital sector.
“Firms” undertake productive activities. Thus, they are all organizations which employ the factors of production to produce goods and services.
“Households” are consuming entities and represent the factors of production, who receive payment for services rendered by them to firms. Households consume the goods and services that are produced by the firms.
“The Government sector” refers to the economic transactions of public bodies at all levels, centre, state and local.
The main function of the government is to provide social goods like defence, public health, education, etc.
“Rest of the world sector” relates to international economic transactions of the country. It contains income, export and import transactions, external loan transaction, and allied overseas investment income and payments.
“Capital sector” refers to saving and investment activities. It includes the transactions of banks, insurance corporations, financial houses, and other agencies of the money market.

Samacheer Kalvi 12th Economics National Income Additional Questions

Part – A
I. Multiple Choice Questions.

Question 1.
Who first introduced the concept of national Income?
Answer:
(a) Simon Kuznets
(b) Karl Marx
(c) Marshall
(d) Adam Smith
Answer:
(a) Simon Kuznets

Question 2.
………………. is the total market value of final goods and services produced with in the country during a year?
(a) GNP
(b) NDP
(c) GDP
(d) NNP
Answer:
(c) GDP

Question 3.
……………………. is also known as Disposable Personal Income?
(a) Personal Income
(b) Disposable Income
(c) Consumer Income
(d) Product Income
Answer:
(b) Disposable Income

Question 4.
………………………. is great importance for the economy of a country?
(a) Personal Income
(b) National Income
(c) Industry Income
(d) Village Income
Answer:
(b) National Income

Question 5.
…………………….. helps to build economic models both in short run and long run?
(a) National Income
(b) Personal Income
(c) Per Capita Income
(d) State Income
Answer:
(a) National Income

Question 6.
……………….. Sector refer to Saving and Investment activities?
(a) Government
(b) World
(c) Capital
(d) Accounting
Answer:
(c) Capital

Question 7.
The Economy is divided into the ………………….. sectors?
(a) two
(b) three
(c) four
(d) five
Answer:
(d) five

Question 8.
…………………….. is considered as a better Indicator of economic welfare?
(a) PQLI
(b) NNP
(c) GDP
(d) NNP
Answer:
(a) PQLI

Question 9.
……………………. means the total money value of all final goods and services produced in a country?
(a) Personal Income
(b) Disposable Income
(c) National Income
(d) Per Capita Income
Answer:
(c) National Income

Question 10.
While assessing sectoral contribution to GDP, the economy is Sectors?
(a) two
(b) three
(c) four
(d) five
Answer:
(b) three

Question 11.
The growth of an economy is indicated by an –
(a) increase in general price level
(b) increase in National Income
(c) increase in contribution of agriculture
(d) increase in Investment
Answer:
(b) increase in National Income

Question 12.
Per Capital Income of an economy can be established by –
(a) Dividing GDP by population
(b) dividing GNP by population
(c) multiplying GNP by population
(d) Multiplying GDP by population
Answer:
(b) dividing GNP by population

Question 13.
Write the Four Sector Model of National Income?
(а) Y = C + I + G + (X – M)
(b) Y = C + I + G + X
(c) Y = C + I + G + M
(d) Y – C + I + G (M – X)
Answer:
(а) Y = C + I + G + (X – M)

Question 14.
Which includes profits earned from Capital Invested abroad?
(a) GNP
(b) GDP
(c) NNP
(d) NDP
Answer:
(a) GNP

Question 15.
Write two components of National Income?
(a) Consumers and producers
(b) Consumers and Industries
(c) Consumers and agricultures
(d) Agricultures and Industries
Answer:
(a) Consumers and producers

Question 16.
The country’s economic performance has been measured by Indicators of –
(a) per Capita Income
(b) national Income
(c) per People’s Income
(d) state Income
Answer:
(b) national Income

Question 17.
NNP is arrived by deducting value of depreciation from –
(a) NDP
(b) GDP
(c) GNP
(d) NNP
Answer:
(c) GNP

Question 18.
Income Method of National Income is the side of our National Income?
(a) Production
(b) Agriculture
(c) Income
(d) Distribution
Answer:
(d) Distribution

Question 19.
The difference between NNP and NDP is –
(a) net Factor Income from abroad
(b) depreciation
(c) current transfer
(d) direct taxes
Answer:
(a) net Factor Income from abroad

Question 20.
In …………………… method, the measures of GDP?
(a) Income
(b) Expenditure
(c) Product
(d) Capital
Answer:
(c) Product

Question 21.
………………… is measure of Income flow from production.
(a) Per Capita Income
(b) National Income
(c) Personal Income
(d) Income method
Answer:
(b) National Income

Question 22.
In estimating national Income, Net value added method is also known as –
(a) income Method
(b) expenditure Method
(c) product Method
(d) investment Method
Answer:
(c) product Method

Question 23.
National Income as commonly understood by everyone refers to –
(a) GNP
(b) GDP
(c) NDP
(d) NNP
Answer:
(d) NNP

Question 24.
Economic growth is determined by changes in ……………………… National income of the country.
(a) Real
(b) Total
(c) True
(d) GDP
Answer:
(c) True

Question 25.
GDP is measure of an economy’s total ………………………..
(a) inflation
(b) deflation
(c) product
(d) output
Answer:
(d) output

II. Match the following and choose the correct answer by using codes given below:

Question 1.
A. Nominal Income – (i) Facrtor earninig method
B. Production – (ii) National Income
C. Income Method – (iii) Final value of goods
D. Expenditure Method – (iv) Value added method
Codes:
(a) A (ii) B (iv) C (i) D (iii)
(b) A (iii) B(ii) C (iv) D (i)
(c) A (ii) B (iv) C (iii) D (i)
(d) A (iv) B (iii) C (i) D (ii)
Answer:
(a) A (ii) B (iv) C (i) D (iii)

Question 2.
A. GDP – (i) NNP
B. Net Income Abroad – (ii) Foreign trade excluded
C. GNP – Depreciation – (iii) X – M
D. Net National Product – (iv) GNP – Depreciation
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (ii) B (iii) C (i) D (iv)
(c) A (iv) B (i) C (ii) D (iii)
(d) A (iii) B (ii) C (iv) D (i)
Answer:
(b) A (ii) B (iii) C (i) D (iv)

Question 3.
A. Per Capita Income – (i) Half of our National Income
B. Purchasing power of Income – (ii) C + I + G + (X – M)
C. Service Sector – (iii) Standard of Living
D. Expenditure method – (iv) National Income
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (iv) B (iii) C (i) D (ii)
(c) A (ii) B (i) C (iii) D (iv)
(d) A (iii) B (iv) C (i) D (ii)
Answer:
(d) A (iii) B (iv) C (i) D (ii)

Question 4.
A. Labour Income – (i) Profit and Interest
B. Capital Income – (ii) Domestic Factor Income
C. Mixed Income – (iii) Wages and Salaries
D. National Income – (iv) Farming, Sole proprietorship
Codes:
(a) A (i) B (ii) C (iv) D (iv)
(b) A (i) B (iii) C (ii) D (i)
(c) A (iii) B (i) C (iv) D (ii)
(d) A (iv) B (ii) C (ii) D (iii)
Answer:
(c) A (iii) B (i) C (iv) D (ii)

Question 5.
A. Income Method – (i) Outlay Method
B. Expenditure Method – (ii) Y = w + r + π + 7t + (R – P)
C. Income Method – (iii) GNP = C + I + G + (X-M)
D. Expenditure Method – (iv) Factor Earning Method
Codes:
(a) A (ii) B (i) C (iv) D (iii)
(b) A (i) B (ii) C (iii) D (iv)
(c) A (iii) B (ii) C (i) D (iv)
(d) A (i) B (iv) C (iii) D (ii)
Answer:
(a) A (ii) B (i) C (iv) D (iii)

III. State whether the statements are true or false.

Question 1.
(i) Net Factor Income earned abroad is always positive.
(ii) Per Capita Income is influenced vastly by population growth.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(d) (i) is false but (ii) is true

Question 2.
(i) Income Method estimates National Income from the production side.
(ii) The value added method is also known as output method.

(a) Both (i) and (ii) are true
(b) Both (0 and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(d) (i) is false but (ii) is true

Question 3.
(i) National Income at current prices is vastly influenced by a rise in general price levels.
(ii) Percentage share of agriculture sector in the national income is increasing.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(c) (i) is true but (ii) is false

Question 4.
(i) GNP is Crude Indicator for living standard.
(ii) The non – resident Indian income will be added to GDP to arrive at our GNP.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 5.
(i) Secondary Sector is Agriculture.
(ii) Tertiary Sector is Industry.
(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(b) Both (i) and (ii) are false

IV. Which of the following is correctly matched:

Question 1.
(a) Disposable Income – Gross National Product
(b) Three Method – Domestic Income
(c) Parallel Economy – Industries
(d) Transfer Earnings – Medical payments
Answer:
(a) Disposable Income – Gross National Product

Question 2.
(a) National Income – Employment
(b) GDP Indicates – Productive capacity
(c) Output = Income = – Price
(d) Primary Sector – Banking
Answer:
(b) GDP Indicates – Productive capacity

Question 3.
(a) Expenditure Method – Per Capita Income
(b) Product Method – Self consumption
(c) Income Method – Factor Earning Method
(d) Revenue Method – Outlay Method
Answer:
(c) Income Method – Factor Earning Method

Question 4.
(a) Labour Income – Farming, Sole proprietorship
(b) Capital Income – Profit, Interest, Dividend & Royalty
(c) Mixed Income – Domestic Factor Income
(d) National Income – Wages and Salaries
Answer:
(b) Capital Income – Profit, Interest, Dividend & Royalty

Question 5.
(a) PQLI – Physical Quantity of Life Index
(b) PQLI – Personal Quantity of Life Index
(c) PQLI – Personal Quality of Life Index
(d) PQLI – Physical Quality of Life Index
Answer:
(d) PQLI – Physical Quality of Life Index

V. Which of the following is not correctly matched:

Question 1.
(a) Simon Kuznets introduced – National Income
(b) Illegal activities are – Gambling and Smuggling
(c) Product Method, the measures – GDP
(d) Income Method – Expenditure Method
Answer:
(a) Income Method – Expenditure Method

Question 2.
(a) Disposable Income – Disposable Personal Income
(b) Per Capita Income – The average income of a person
(c) Real Income – Production
(d) Nominal Income – National Income
Answer:
(c) Real Income – Production

Question 3.
(a) Product Method – Inventory Method
(b) Income Method – Factor Earning Method
(c) Expenditure Method – Outlay Method
(d) Value added Method – Transfer Payments
Answer:
(d) Value added Method – Transfer Payments

Question 4.
(a) Two Sector Model – Households, firms
(b) Four Sector Economy – Foreign Earning Method
(c) Four Sector Model – outlay Method
(d) Major Problem – Transfer Payments
Answer:
(a) Two Sector Model – Households, firms

Question 5.
(a) Transfer payments – Pensions, unemployement
(b) Unpaid services – House Wife
(c) Illegal activities – Smuggling
(d) The Government Sector – Private Enterprises
Answer:
(d) The Government Sector – Private Enterprises

VI. Pick the odd one out.

Question 1.
The concepts used in Measuring National Income?
(a) GDP
(b) NNP
(c) NNP at factor cost
(d) Personal Expenditure
Answer:
(d) Personal Expenditure

Question 2.
GNP – Includes these types of final goods and services?
(a) Consumption
(b) Investment
(c) Government
(d) Capital
Answer:
(d) Capital

Question 3.
The Expenditure Method precautions are –
(a) Second hand goods should not be included
(b) Purchase of shares and bonds are not be included
(c) Transfer payments of old age pension added
(d) Avoid double counting
Answer:
(c) Transfer payments of old age pension added

Question 4.
The Economy is divided into the following sectors –
(a) Investment Sector
(b) Firms
(c) Households
(d) Government Sector
Answer:
(a) Investment Sector

Question 5.
Dispsoable Income is the individuals Income after the payment of Income tax?
(a) Disposable Income = Personal Income – Direct tax
(b) Disposable Income = Consumption + Saving
(c) Disposable Income = Agriculture + Industry
(d) Disposable Income = Individual Income + Income Tax
Answer:
(c) Disposable Income = Agriculture + Industry

VII. Assertion and Reason.

Question 1.
Assertion (A): National Income is a measure of the total value of the goods and services produced in an economy for a year.
Reason (R): GNP – is the total value of output produced and income received in a year by domestic residence of a country.

(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not the correct explanation to ‘A’
(c) ‘A’ is true but ‘R’ is false (id) ‘A’ is false but ‘R’ is true
(d) ‘A’ is false but ‘R’ is true
Answer:
(a) Both ‘A’ and ‘R’ are true and ‘R’ is the correct explanation to ‘A’

Question 2.
Assertion (A): Product method measures the output of the country.
Reason (R): Product method measures the agriculture field only.

Question 3.
Assertion (A): Deflation is the common feature in almost all the economies.
Reason (R): Inflation is the common feature in almost all the economies.

Question 4.
Assertion (A): The Income method is called Factor Earning Method.
Reason (R): This method approaches National Income from the distribution side.

Question 5.
Assertion (A): The Expenditure method is called outlay method.
Reason (R): This method is used only private sector.

Part – B
Answer The Following Questions In One or Two Sentences.

Question 1.
Write the Factor Incomes group?
Answer:
Factor incomes are grouped under labour income, capital income and mixed income.

Labour income – Wages and salaries, fringe benefits, employer’s contribution to social security.
Capital income – Profit, interest, dividend and royalty
Mixed income – Farming, sole proprietorship and other professions.

Question 2.
Write the headlines of difficulties in Measuring National Income?
Answer:
Difficulties in Measuring National Income:

Transfer payments:
Difficulties in assessing depreciation allowance:
Unpaid services:
Income from illegal activities:
Production for self-consumption and changing price:
Capital Gains:
Statistical problems

Question 3.
Define “Capital Gains”?
Answer:
The problem also arises with regard to capital gains. Capital gains arise when a capital asset such as a house, other property, stocks or shares, etc. is sold at higher price than was paid for it at the time of purchase. Capital gains are excluded from national income.

Question 4.
Define “Social and Environmental Cost”?
Answer:
Social and Environmental Cost: While producing economic goods, many environmental and social bads are also generated. Hence, they also must be considered while enumerating National income.

Question 5.
Define “National Income & Erosion of National Wealth”?
Answer:
For achieving higher GDP, larger natural resources are being depleted or damaged. This means reduction of potential for future growth. Hence, it is suggested that while assessing national income, loss of natural resources should be subtracted from national income.

Part – C
Answer The Following Questions In One Paragraph.

Question 1.
Write the statistical problems?
Answer:
The following are the some of the statistical problems:

Accurate and reliable data are not adequate, as farm output in the subsistence sector is not completely informed. In animal husbandry, there are no authentic production data available.
Different languages, customs, etc., also create problems in computing estimates.
People in India are indifferent to the official inquiries. They are in most cases non – cooperative also.
Most of the statistical staff are untrained and inefficient.

Question 2.
Discuss the estimating the national income through the Income Method precautions?
Answer:

Transfer payments are not to be included in estimation of national income as these payments are not received for any services provided in the current year such as pension, social insurance etc.
The receipts from the sale of second hand goods should not be treated as part of national income as they do not create new flow of goods or services in the current year.
Windfall gains such as lotteries are also not to be included as they do not represent receipts from any current productive activity.
Corporate profit tax should not be separately included as it has been already included as a part of company profit.

Question 3.
What is Market price and Equations?
Answer:
Samacheer Kalvi 12th Economics Solutions Chapter 2 National Income

Part – D
Answer The Following Questions In One Page.

Question 1.
Write the gross value of the farm output in India?
Answer:
In India, the gross value of the farm output is obtained as follows:

Total production of 64 agriculture commodities is estimated. The output of each crop is measured by multiplying the area sown by the average yield per hectare.
The total output of each commodity is valued at market prices.
The aggregate value of total output of these 64 commodities is taken to measure the gross value of agricultural output.
The net value of the agricultural output is measured by making deductions for the cost of seed, manures and fertilisers, market charges, repairs and depreciation from the gross value.

Question 2.
Explain the Expenditure Method (Outlay Method) precautions?
Answer:
Precautions:

Second hand goods:
The expenditure made on second hand goods should not be included.
Purchase of shares and bonds:
Expenditures on purchase of old shares and bonds in the secondary market should not be included.
Transfer payments:
Expenditures towards payment incurred by the government like old age pension should not be included.
Expenditure on intermediate goods:
Expenditure on seeds and fertilizers by farmers, cotton and yam by textile industries are not to be included to avoid double counting. That is only expenditure on final products are to be included.

Question 3.
Explain the Importance of Factor Cost?
Answer:
Samacheer Kalvi 12th Economics Solutions Chapter 2 National Income

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Samacheer Kalvi 12th Economics Solutions Chapter 11 Economics of Development and Planning

April 24, 2024

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Tamilnadu Samacheer Kalvi 12th Economics Solutions Chapter 11 Economics of Development and Planning

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Samacheer Kalvi 12th Economics Economics of Development and Planning Text Book Back Questions and Answers

Part – A
Multiple Choice Questions.

Question 1.
“Redistribution with Growth” became popular slogan under which approach?
(a) Traditional approach
(b) New welfare oriented approach
(c) Industrial approach
(d) None of the above
Answer:
(b) New welfare oriented approach

Question 2.
Which is not the feature of economic growth?
(a) Concerned with developed nations
(b) Gradual change
(c) Concerned with quantitative aspect
(d) Wider concept
Answer:
(d) Wider concept

Question 3.
Which among the following is a characteristic of underdevelopment?
(a) Vicious circle of poverty
(b) Rising mass consumption
(c) Growth of Industries
(d) High rate of urbanization
Answer:
(a) Vicious circle of poverty

Question 4.
The non – economic determinant of economic development ………………………..
(a) Natural resources
(b) Human resource
(c) Capital formation
(d) Foreign trade
Answer:
(b) Human resource

Question 5.
Economic growth measures the ………………………..
(a) Growth of productivity
(b) Increase in nominal income
(c) Increase in output
(d) None of the above
Answer:
(c) Increase in output

Question 6.
The supply side vicious circle of poverty suggests that poor nations remain poor because
(a) Saving remains low
(b) Investment remains low
(c) There is a lack of effective government
(d) a and b above
Answer:
(d) a and b above

Question 7.
Which of the following plan has focused on the agriculture and rural economy?
(a) People’s Plan
(b) Bombay Plan
(c) Gandhian Plan
(d) Vishveshwarya Plan
Answer:
(c) Gandhian Plan

Question 8.
Arrange following plans in correct chronological order ………………………..
(a) People’s Plan
(b) Bombay Plan
(c) Jawaharlal Nehru Plan
(d) Vishveshwarya Plan
Answer choices
(a) (i) (ii) (iii) (iv)
(b) (iv) (iii) (ii) (i)
(c) (i) (ii) (iv) (iii)
(d) (ii) (i) (iv) (iii)
Answer:
(b) (iv) (iii) (ii) (i)

Question 9.
M.N. Roy was associated with ………………………..
(a) Congress Plan
(b) People’s Plan
(c) Bombay Plan
(d) None of the above
(b) People’s Plan

Question 10.
Which of the following country adopts indicative planning?
(a) France
(b) Germany
(c) Italy
(d) Russia
Answer:
(b) Germany

Question 11.
Short – term plan is also known as ………………………..
(a) Controlling Plans
(b) De – controlling Plans
(c) Rolling Plans
(d) De – rolling Plans
Answer:
(a) Controlling Plans

Question 12.
Long – term plan is also known as ………………………..
(a) Progressive Plans
(b) Non – progressive Plans
(c) Perspective Plans
(d) Non – perspective Plans
Answer:
(c) Perspective Plans

Question 13.
The basic philosophy behind long – term planning is to bring ……………………….. changes in the economy?
(a) Financial
(b) Agricultural
(c) Industrial
(d) Structural
Answer:
(c) Industrial

Question 14.
Sarvodaya Plan was advocated by ………………………..
(a) Mahatma Gandhi
(b) J.P. Narayan
(c) S. N Agarwal
(d) Structural
Answer:
(b) J.P. Narayan

Question 15.
Planning Commission was set up in the year ………………………..
(a) 1950
(b) 1951
(c) 1947
(d) 1948
Answer:
(a) 1950

Question 16.
Who wrote the book ‘The Road to Serfdom’?
(a) Friedrich Hayek
(b) H.R. Hicks
(c) David Ricardo
(d) Thomas Robert Malthus
Answer:
(a) Friedrich Hayek

Question 17.
Perspective plan is also known as ………………………..
(a) Short – term plan
(b) Medium – term plan
(c) Long – term plan
(d) None of the above
Answer:
(c) Long – term plan

Question 18.
NITI Aayog is formed through ………………………..
(a) Presidential Ordinance
(b) Allocation of business rules by President of India
(c) Cabinet resolution
(d) None of the above
Answer:
(c) Cabinet resolution

Question 19.
Expansion of NITI Aayog?
(a) National Institute to Transform India
(b) National Institute for Transforming India
(c) National Institution to Transform India
(d) National Institution for Transforming India
Answer:
(d) National Institution for Transforming India

Question 20.
The Chair Person of NITI Aayog is ………………………..
(a) Prime Minister
(b) President
(c) Vice – President
(d) Finance Minister
Answer:
(a) Prime Minister

Part – B
Answer The Following Questions In One or Two Sentences.

Question 21.
Define economic development?
Answer:

Economic development refers to the problems of underdeveloped countries and economic growth to those of developed countries.
Economic development deals with the problems of UDCs. Change is discontinuous and spontaneous.
Economic development is not determined by any single factor. Economic development depends on Economic, Social, Political and Religious factors.

Question 22.
Mention the indicators of development?
Answer:

Economic development is regarded as a process whereby there is an increase in the consumption of goods and services by individuals.
From the welfare perspective, economic development is defined as a sustained improvement in health, literacy and standard of living.

Question 23.
Distinguish between economic growth and development?
Answer:
Economic Growth:

Deals with the problems of Developed countries
Change is gradual and steady
Means more output
Concerns Quantitative aspects i.e. increase in per capita income
Narrow

Economic Development:

Deals with the problems of UDCs
Change is discontinuous and spontaneous
Means not only more output but also its composition
Quantitative as well as Qualitative
Wider concept Development = Growth + Change

Question 24.
What is GNP?
Answer:
Gross National Product (GNP):

GNP is the total market value of all final goods and services produced within a nation in a particular year, plus income earned by its citizens (including income of those located abroad), minus income of non – residents located in that country.
GNP is one measure of the economic condition of a country, under the assumption that a higher GNP leads to a higher quality of living, all other things being equal.

Question 25.
Define economic planning?
Answer:

Economic Planning is “collective control or suppression of private activities of production and exchange”. – Robbins
“Economic Planning in the widest sense is the deliberate direction by persons in – charge of large resources of economic activity towards chosen ends”. – Dalton

Question 26.
What are the social indicators of economic development?
Answer:
Social Indicators:

Social indicators are normally referred to as basic and collective needs of the people.
The direct provision of basic needs such as health, education, food, water, sanitation and housing facilities check social backwardness.

Question 27.
Write a short note on NITI Aayog?
Answer:

NITI Aayog (National Institution for Transforming India) was formed on January 1, 2015 through a Union Cabinet resolution.
NITI Aayog is a policy think-tank of the Government of India. It replaced the Planning Commission from 13th August, 2014.
The Prime Minister is the Chairperson of NITI Aayog and Union Ministers will be Ex – officio members.
The Vice – Chairman of the NITI Aayog is the functional head and the first Vice – Chairman was Arvind Panangariya.

Part – C
Answer The Following Questions In One Paragraph.

Question 28.
Elucidate major causes of vicious circle of poverty with diagram?
Answer:
Samacheer Kalvi 12th Economics Solutions Chapter 11 Economics of Development and Planning

There are circular relationships known as the ‘vicious circles of poverty’ that tend to perpetuate the low level of development in Less Developed Countries (LDCs).
Nurkse explains the idea in these words: “It implies a circular constellation of forces tending to act and react upon one another in such a way as to keep a poor country in a state of poverty.
For example, a poor man may not have enough to eat; being underfed, his health may be weak; being physically weak, his working capacity is low, which means that he is poor, which in turn means that he will not have enough to eat and so on.
A situation of this sort relating to a country as a whole can be summed up in the proposition: “A county is poor because the country is poor”.
The vicious circle of poverty operates both on the demand side and the supply side.
On the supply side, the low level of real income means low savings.
The low level of saving leads to low investment and to deficiency of capital.
The deficiency of capital, in turn, leads to low levels of productivity and back to low income. Thus the vicious circle is complete from the supply side.
The demand-side of the vicious circle is that the low level of real income leads to a low level of demand which, in turn, leads to a low rate of investment and hence back to deficiency of capital, low productivity and low income.

Question 29.
What are the non – economic factors determining development?
Answer:

Human Resource
Technical Know – how
Political Freedom
Social Organization
Corruption free administration
Desire for Development
Moral, ethical and social values (viii) Casino Capitalism
Patrimonial Capitalism

Non – Economic Factors:
‘Economic Development has much to do with human endowments, social attitudes, political conditions and historical accidents. Capital is a necessary but not a sufficient condition of progress.’

(I) Human Resources:

Human resource is named as human capital because of its power to increase productivity and thereby national income.
There is a circular relationship between human development and economic growth.
A healthy, educated and skilled labour force is the most important productive asset.
Human capital formation is the process of increasing knowledge, skills and the productive capacity of people.

(II) Technical Know – how:
As the scientific and technological knowledge advances, more and more sophisticated techniques steadily raise the productivity levels in all sectors.

(III) Political Freedom:
The process of development is linked with the political freedom.

(IV) Social Organization:
People show interest in the development activity only when they feel that the fruits of development will be fairly distributed.

(V) Corruption free administration:

Corruption is a negative factor in the growth process.
Unless the countries root-out corruption in their administrative system, the crony capitalists and traders will continue to exploit national resources.

(VI) Desire for development:
The pace of economic growth in any country depends to a great extent on people’s desire for development.

(VII) Moral, ethical and social values:

These determine the efficiency of the market, according to Douglas C. North.
If people are not honest, market cannot function.

(VIII) Casino Capitalism:
If People spend larger propotion of their income and time on entertainment liquor and other illegal activities, productive activities may suffer, according to Thomas Piketty.

(IX) Patrimonial Capitalism:
If the assets are simply passed on to children from their parents, the children would not work hard, because the children do not know the value of the assets.

Question 30.
How would you break the vicious circle of poverty?
Answer:
Breaking the Vicious Circle of Poverty:

The vicious circle of poverty is associated with low rate of saving and investment on the supply side.
In UDCs the rate of investment and capital formation can be stepped up without reduction in consumption. For this, the marginal rate of savings is to be greater than average rate of savings.
To break the vicious circle on the demand side, Nurkse suggested the strategy of balanced growth.
If investment is made in several industries simultaneously the workers employed in various industries will become consumers of each other’s products and will create demand for one another.
The balanced growth i.e. simultaneous investment in large number of industries creates mutual demand. Thus, through the strategy of balanced growth, vicious circle of poverty operating on the demand side of capital formation can be broken.

Question 31.
Trace the evolution of economic planning in India?
Answer:
The evolution of planning in India is stated below:

(I) Sir M. Vishveshwarya (1934):
A prominent engineer and politician made his first attempt in laying foundation for economic planning in India in 1934 through his book, “Planned Economy of India”. It was a 10 year plan.

(II) Jawaharlal Nehru (1938):
Set – up “National Planning Commission” by a committee but due to the changes in the political era and second World War, it did not materialize.

(III) Bombay Plan (1940):
The 8 leading industrialists of Bombay presented “Bombay Plan”. It was a 15 Year Investment Plan.

(IV) S.N Agarwal (1944):
Gave the “Gandhian Plan” focusing on the agricultural and rural economy.

(V) M.N. Roy (1945):
Drafted ‘People’s Plan”. It was aiming at mechanization of agricultural production and distribution by the state only.

(VI) J.P. Narayan (1950):
Advocated, “Sarvodaya Plan” which was inspired by Gandhian Plan and with the idea of Vinoba Bhave. It gave importance not only for agriculture, but encouraged small and cottage industries in the plan.

Question 32.
Describe the case for planning?
Answer:
The economic planning is justified on the following grounds.
(I) To accelerate and strengthen market mechanism:
The market mechanism works imperfectly in underdeveloped countries because of the ignorance and unfamiliarity with it. A large part of the economy comprises the non-monetized sector.

(II) To remove unemployment:
Capital being scarce and labour being abundant, the problem of providing gainful employment opportunities to an ever-increasing labour force is a difficult task.

(III) To achieve balanced development:
In the absence of sufficient enterprise and initiative, the planning authority is the only institution for planning the balanced development of the economy.

(a) Development of Agriculture and Industrial Sectors:
The need for developing the agriculture sector along with the industrial sector arises from the fact that agriculture and industry are interdependent.

(b) Development of Infrastructure:
The agriculture and industrial sectors cannot develop in the absence of economic and social overheads. The building of canals, roads, railways, power stations, etc., is indispensable for agricultural and industrial development.

(c) Development of Money and Capital Markets:
The expansion of the domestic and foreign trade requires not only the development of agricultural and industrial sectors along with social and economic overheads but also the existence of financial institutions.

(IV) To remove poverty and inequalities:
Planning is the only path open to underdeveloped countries, for raising national and per capita income, reducing inequalities and poverty and increasing employment opportunities.

Question 33.
Distinguish between functional and structural planning?
Answer:
Functional planning:
Functional planning refers to that planning which seeks to remove economic difficulties by directing all the planning activities within the existing economic and social structure.

Structural planning:
The structural planning refers to a good deal of changes in the socio-economic framework of the country. This type of planning is adopted mostly in under developed countries.

Question 34.
What are the functions of NITI Aayog?
Answer:
Functions of NITI Aayog:
(I) Cooperative and Competitive Federalism:
To enable the States to have active participation in the formulation of national policy.

(II) Shared National Agenda:
To evolve a shared vision of national development priorities and strategies with the active involvement of States.

(III) Decentralized Planning:
To restructure the planning process into a bottom-up model.

(IV) Vision and Scenario Planning:
To design medium and long – term strategic frameworks towards India’s future.

(V) Network of Expertise:
To mainstream external ideas and expertise into government policies and programmes through a collective participation.

(VI) Harmonization:
To facilitate harmonization of actions across different layers of government, especially when involving cross-cutting and overlapping issues across multiple sectors; through communication, coordination,
collaboration and convergence amongst all the stakeholders.

(VII) Conflict Resolution:
To provide platform for mutual consensus to inter – sectoral, interdepartmental, inter – state as well as centre-state issues for all speedy execution of the government programmes.

(VIII) Coordinating Interface with the World:
It will act nodal point to harness global expertise and resources coming from International organizations for India’s developmental process.

(IX) Internal Consultancy:
It provides internal consultancy to Central and State governments on policy and programmes.

(X) Capacity Building:
It enables to provide capacity building and technology up – gradation across government, benchmarking with latest global trends and providing managerial and technical know-how.

(XI) Monitoring and Evaluation:
It will monitor the implementation of policies and progammes and evaluate the impacts.

Part – D
Answer The Following Questions In About A Page.

Question 35.
Discuss the economic determinants of economic development?
Answer:
Determinants of Economic Development:
Economic development is not determined by any,single factor. Economic development depends on Economic, Social, Political and Religious factors.
Economic and Non – Economic Factors:

Samacheer Kalvi 12th Economics Solutions Chapter 11 Economics of Development and Planning

Economic Factors:

1. Natural Resource:
The principal factor affecting the development of an economy is the availability of natural resources. The existence of natural resources in abundance is essential for development.

2. Capital Formation:
Capital formation is the main key to economic growth. Capital formation refers to the net addition to the existing stock of capital goods which are either tangible like plants and machinery or intangible like health, education and research.

3. Size of the Market:
Large size of the market would stimulate production, increase employment and raise the National per capita income. That is why developed countries expand their market to other countries through WTO.

4. Structural Change:
Structural change refers to change in the occupational structure of the economy. Any economy of the country is generally divided into three basic sectors: Primary sector such as agricultural, animal husbandry, forestry, etc; Secondary sector such as industrial production, constructions and Tertiary sector such as trade, banking and commerce.

5. Financial System:
Financial system implies the existence of an efficient and organized banking system in the country.

6. Marketable Surplus:
Marketable surplus refers to the total amount of farm output cultivated by farmers over and above their family consumption needs. This is a surplus that can be sold in the market for earning income.

7. Foreign Trade:
The country which enjoys favorable balance of trade and terms of trade is always developed. It has huge forex reserves and stable exchange rate.

8. Economic System:
The countries which adopt free market mechanism (laissez faire) enjoy better growth rate compared to controlled economies.

1. Human Resources:
Human resource is named as human capital because of its power to increase productivity and thereby national income. There is a circular relationship between human development and economic growth. A healthy, educated and skilled labour force is the most important productive asset. Human capital formation is the process of increasing knowledge, skills and the productive capacity of people.

2. Technical Know-how:
As the scientific and technological knowledge advances, more and more sophisticated techniques steadily raise the productivity levels in all sectors.

3. Political Freedom:
The process of development is linked with the political freedom.

4. Social Organization:
People show interest in the development activity only when they feel that the fruits of development will be fairly distributed.

5. Corruption free administration:
Corruption is a negative factor in the growth process. Unless the countries root-out corruption in their administrative system, the crony capitalists and traders will continue to exploit national resources.

6. Desire for development:
The pace of economic growth in any country depends to a great extent on people’s desire for development.

7. Moral, ethical and social values:
These determine the efficiency of the market, according to Douglas C. North. If people are not honest, market cannot function.

8. Casino Capitalism:
If People spend larger propotion of their income and time on entertainment liquor and other illegal activities, productive activities may suffer, according to Thomas Piketty.

9. Patrimonial Capitalism:
If the assets are simply passed on to children from their parents, the children would not work hard, because the children do not know the value of the assets.

Question 36.
Describe different types of Planning?
Answer:
Samacheer Kalvi 12th Economics Solutions Chapter 11 Economics of Development and Planning

(I) Democratic Vs Totalitarian:
A form of rule in which the government attempts to maintain ‘total’ control over society, including all aspects of the public and private lives of its citizens.

(II) Centralized Vs Decentralized:

Under centralized planning, the entire planning process in a country is under a central planning authority.
This authority formulates a central plan, fixes objectives, targets and priorities for every sector of the economy.
In other words, it is called ‘planning from above’.

(III) Planning by Direction Vs Inducement:
Under planning by direction, there is a central authority which plans, directs and orders the execution of the plan in accordance with pre-determined targets and priorities.

(IV) Indicative Vs Imperative Planning:

Indicative planning is peculiar to the mixed economies. It has been in practice in France since the Monnet Plan of 1947-50.
In a mixed economy, the private sector and the public sector work together.
Under this plan, the outline of plan is prepared by the Government.
Then it is discussed with the representatives of private management, trade unions, consumer groups, finance institutions and other experts.

(V) Short, Medium and Long term Planning:

Short-term plans are also known as ‘controlling plans’.
They encompass the period of one year, therefore, they are also known as ‘annual plans’

(VI) Financial Vs Physical Planning:
Financial planning refers to the technique of planning in which resources are allocated in terms of money while physical planning pertains to the allocation of resources in terms of men, materials and machinery.

(VII) Functional Vs Structural Planning:
Functional planning refers to that planning which seeks to remove economic difficulties by directing all the planning activities within the existing economic and social structure.

(VIII) Comprehensive Vs Partial Planning:
General planning which concerns itself with the major issues for the whole economy is known as comprehensive planning whereas partial planning is to consider only the few important sectors of the economy.

Question 37.
Bring out the arguments against planning?
Answer:
The arguments against planning are discussed below.
(I) Loss of freedom:

The absence of freedom in decision making may act as an obstacle for economic growth.
Regulations and restrictions are the backbone of a planned economy.
The economic freedom comprises freedom of consumption, freedom of choice of occupation, freedom to produce and the freedom to fix prices for the products.
Under planning, the crucial decisions are made by the Central Planning Authority.

(II) Elimination of Initiative:
Under centralized planning, there will be no incentive for initiatives and innovations.

(a) The absence of private ownership and profit motive discourages entrepreneurs from taking bold decisions and risk taking. Attractive profit is the incentive for searching new ideas, new lines and new, methods.

(b) As all enjoy equal reward under planned economy irrespective of their effort, efficiency and productivity.

(c) The bureaucracy and red tapism which are the features of planned economy, cripple the initiative as they cause procedural delay and time loss.

(III) High cost of Management:

No doubt the fruits of planning such as industrialization, social justice and regional balance are good.
But the cost of management of the economic affairs outweighs the benefits of planning.
Plan formulation and implementation involve engagement of an army of staff for data collection and administration.

(IV) Difficulty in advance calculations:

Price mechanism provides for the automatic adjustment among price, demand and supply in a Laissez Faire economy.
The producers and consumers adjust their supply and demand based on price changes.
The arguments against planning are mostly concerned with centralized and totalitarian planning.
The democratic planning, planning by inducement and decentralized planning especially under mixed economies give equal role for private sector and public sector.

Samacheer Kalvi 12th Economics Economics of Development and Planning Additional Questions and Answers

Part – A
I. Multiple Choice Questions.

Question 1.
………………………. defines development strictly in Economic terms.
(a) Traditional approach
(b) New welfare oriented approach
(c) Development approach
(d) Under development approach
Answer:
(a) Traditional approach

Question 2.
New welfare oriented approach is called ……………………….
(a) Economic growth
(b) Economic Development
(c) Redistribution with growth
(d) New Welfare Development
Answer:
(c) Redistribution with growth

Question 3.
Under development refers to that state of an economy is very low levels of Per Capita Income and ……………………….
(a) Low level of productivity
(b) Low level of people
(c) Low level of distribution
(d) Low level of unemployment
Answer:
(a) Low level of productivity

Question 4.
………………………. leads to a higher quality of living all other thing being equal.
(a) GNP
(b) NNP
(c) GDP
(d) NDP
Answer:
(a) GNP

Question 5.
GNP relates to increase in the ………………………. of the Economy.
(a) Per Capita Real Income
(b) Per Capita Finance
(c) Per Capita Economy
(d) Per Capita Natural Resource
Answer:
(a) Per Capita Real Income

Question 6.
………………………. is defined as a sustained improvement in health, literacy and standard of living.
(a) Economic level
(b) Economic welfare
(c) Economic development
(d) Economic goods
Answer:
(c) Economic development

Question 7.
………………………. is called basic needs such as health, education, food, water, sanitation and housing facilities and social backwardness.
(a) Economic Indicators
(b) Social Indicators
(c) Welfare Indicators
(d) State Indicators
Answer:
(b) Social Indicators

Question 8.
Economic development depends on Economic, Soical, Political and ………………………. factors.
(a) Real
(b) Religion
(c) Religious
(d) Welfare
Answer:
(c) Religious

Question 9.
Low level of Development is called ……………………….
(a) Developed countries
(b) Less developed countries
(c) Developed nation
(d) Under developed nation
Answer:
(b) Less developed countries

Question 10.
Price mechanism provides for the automatic adjustment among price, demand and supply in a ………………………. Economy.
(a) Laissez Faire
(b) Developed
(c) Under developed
(d) Planned
Answer:
(a) Laissez Faire

Question 11.
Centralised planning the entire planning process in a country is under a ………………………. authority.
(a) Imperative planning
(b) Planning by direction
(c) Central planning
(d) Long term planning
Answer:
(c) Central planning

Question 12.
………………………. planning by Inducement the people are induced to act in a certain way through various monetary and fiscal measures.
(a) Centralized planning
(b) Planning by direction
(c) Imperative planning
(d) Short term planning
Answer:
(b) Planning by direction

Question 13.
Short term plans are also known as ……………………….
(a) Long term plans
(b) Planning by direction
(c) Centralised planning
(d) Controlling plans
Answer:
(d) Controlling plans

Question 14.
………………………. planning is peculiar to the mixed economies.
(a) Centralised planning
(b) Indicative planning
(c) Planing by direction
(d) Imperative short term planning
Answer:
(b) Indicative planning

Question 15.
………………………. the state is all powerful in preparation and implementation of the plan.
(a) Centralized planning
(b) Planning by direction
(c) Indicative planning
(d) Imperative planning
Answer:
(d) Imperative planning

Question 16.
………………………. planning refers to the technique of planning in which resources are allocated in terms of money.
(a) Financial
(b) Physical
(c) Structural
(d) Functional
Answer:
(a) Financial

Question 17.
………………………. planning pertains to the allocation of resources in terms of men, materials and machinery.
(a) Financial
(b) Physical
(c) Functional
(d) Structural
Answer:
(b) Physical

Question 18.
………………………. planning refers to a good deal of changes in the socio economic framework of the country.
(a) Financial
(b) Physical
(c) Functional
(d) Structural
Answer:
(d) Structural

Question 19.
General planning concerns itself with the major issues for the whole economy is known as ………………………. planning.
(a) comprehensive
(b) Partial
(c) Functional
(d) Structural
Answer:
(a) comprehensive

Question 20.
NITI Aayog was formed on through a ……………………….
(a) Financial resolution
(b) Functional resolution
(c) Comprehensive resolution
(d) Union cabinet
Answer:
(d) Union cabinet

Question 21.
……………………… is a policy think tank of the Government of India.
(a) Comprehensive planning
(b) Partial planning
(c) NITI Aayog
(d) Functional planning
Answer:
(c) NITI Aayog

Question 22.
……………………… to central and state governments on policy and programmes.
(a) Internal consultancy
(b) Interface consultancy
(c) Conflict consultancy
(d) Monitoring consultancy
Answer:
(a) Internal consultancy

Question 23.
A shared vision of national development priorities and strategies with the active involvement of states is called ………………………
(a) Competitive federalism
(b) Shared national agenda
(c) Scenario planning
(d) Network of expertise
Answer:
(b) Shared national agenda

Question 24.
To restructure the planning process into a bottom – up model is called ………………………
(a) Decentralized planning
(b) Scenario planning
(c) Partial planning
(d) Comprehensive planning
Answer:
(a) Decentralized planning

Question 25.
To enable the states to have active participation in the formulation of national policy is called co – operative and ………………………
(a) Competitive federalism
(b) Comprehensive federalism
(c) Partial federalism
(d) Comprehensive federalism
Answer:
(a) Competitive federalism

II. Match The Following And Choose The Correct Answer By Using Codes Given Below.

Question 1.
A. UDC – (i) Economic terms
B. Traditional approach – (ii) Low Per Capita Income
C. Economic Development – (iii) Higher level of living
D. GNP – (iv) Economic growth
Codes:
(a) A (ii) B (i) C (iv) D (iii)
(b) A (i) B (ii) C (i) D (ii)
(c) A (iii) B (iv) C (ii) D (i)
(d) A (iv) B (iii) C (i) D (ii)
Answer:
(a) A (ii) B (i) C (iv) D (iii)

Question 2.
A. Capital formation – (i) Organised banking system
B. Size of the market – (ii) Economic growth
C. Occupational structure – (iii) Increase employment
D. Financial system – (iv) Structural change
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (iii) B (iv) C (i) D (ii)
(c) A (iv) B (i) C (ii) D (iii)
(d) A (ii) B (iii) C (iv) D (i)
Codes:
Answer:
(d) A (ii) B (iii) C (iv) D (i)

Question 3.
A. Human resource – (i) Technical knowledge
B. Technical know-how – (ii) Crony capitalism
C. Political freedom – (iii) Increase productivity
D. Social organization – (iv) Development linked
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (iii) B (i) C (iv) D (ii)
(c) A (iv) B (iii) C (ii) D (i)
(d) A (ii) B (iii) C (iv) D (i)
Answer:
(b) A (iii) B (i) C (iv) D (ii)

Question 4.
A. Casino capitalism – (i) 1948
B. First five year plan – (ii) 1950
C. Industrial policy – (iii) 1951 – 1956
D. Plan era – (iv) Illegal activities
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (ii) B (iv) C (iii) D (i)
(c) A (iii) B (iv) C (ii) D (i)
(d) A (iv) B (iii) C (i) D (ii)
Answer:
(d) A (iv) B (iii) C (i) D (ii)

Question 5.
A. Patrimonial capitalism – (i) Collective control
B. Vicious circle of poverty – (ii) LDC
C. Economic planning – (iii) Solved union econokic planning
D. Industrial super power – (iv) Children would not work hard
Codes:
(a) A (i) B (iii) C (ii) D (i)
(b) A (ii) B (iv) C (iii) D (i)
(c) A (iv) B (ii) C (i) D (iii)
(d) A (iii) B (i) C (iv) D (ii)
Answer:
(d) A (iii) B (i) C (iv) D (ii)

III. State Whether The Statements Are True or False.

Question 1.
(i) There are two main approaches to the concept of development viz
(1) The traditional approach
(2) The new welfare oriented approach.
(ii) The traditional approach defines development strictly in economic terms.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 2.
(i) Economic development was redefined in terms of reduction of poverty, inequality and unemployment with in the context of a growing economy.
(ii) New welfare oriented approach is “Redistribution with growth”.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 3.
(i) GNP is the total market value of all final goods and services.
(ii) GNP leads low level of living.

(a) Both (i) and (ii) are true
(b) (i) is true but (ii) is false
(c) Both (i) and (ii) are false
(d) (i) is false but (ii) is true
Answer:
(b) (i) is true but (ii) is false

Question 4.
(i) Social Indicators are basic and collective needs of the people.
(ii) The basic needs are agriculture and Industry.

(a) Both (i) and (ii) are true
(b) (i) is true but (ii) is false
(c) Both (i) and (ii) are false
(d) (i) is false but (ii) is true
Answer:
(b) (i) is true but (ii) is false

Question 5.
(i) Capital formation is the main key to economic growth.
(ii) Capital formation helps to increase the population.

(a) (i) is true but (ii) is false
(b) Both (i) and (ii) are false
(c) Both (i) and (ii) are true
(d) (i) is false but (ii) is true
Answer:
(a) (i) is true but (ii) is false

IV. Which of The Following Is Correctly Matched.

Question 1.
(a) Sir M. Vishveshwarya – 1940
(b) Jawaharlal Nehru – 1934
(c) Bombay plan – 1938
(d) S.N. Agarwal – 1944
Answer:
(d) S.N. Agarwal – 1944

Question 2.
(a) Planned Economy of India – S.N. Agarwal
(b) National planning commission – Jawaharlal Nehru
(c) Bombay plan – Sir M. Vishveshwarya
(d) Gandhianplan – Investment plan
Answer:
(c) Bombay plan – Sir M. Vishveshwarya

Question 3.
(a) NITI Aayog – Union cabinet resolution
(b) Financial planning – Controlling plans
(c) Short term plans – Technique planning
(d) Indicative planning – Capitalist economy
Answer:
(a) NITI Aayog – Union cabinet resolution

Question 4.
(a) UDC – Vicious circle of poverty
(b) Rural economy – Peoples plan
(c) Redistribution with growth – Industrial approach
(d) Controlling plans – Polling plans
Answer:
(a) UDC – Vicious circle of poverty

Question 5.
(a) H.R. Hicks – The road to serfdom
(b) Sarvodaya plan – M.N. Roy
(c) Perspective plan – Long term plan
(d) Modernisation – Industrialization
Answer:
(c) Perspective plan – Long term plan

V. Which of The Following Is Not Correctly Matched.

Question 1.
(a) Structural changes – Modernization
(b) Functional planning – Remove Economic difficulties
(c) Capitalist economy – Partial planning
(d) People’s plan – N.S.C. Bose
Answer:
(d) People’s plan – N.S.C. Bose

Question 2.
(a) Market economy – Capitalist economy
(b) Industry – Socialist economy
(c) J.P. Narayan – Bombay plan
(d) S.N. Agarwal – Gandhian plan
Answer:
(c) J.P. Narayan – Bombay plan

Question 3.
(a) 1934 – Jawaharlal Nehru
(b) 1950 – J.P. Narayan
(c) 1945 – M.N. Roy
(d) 1944 – S.N. Agarwal
Answer:
(a) 1934 – Jawaharlal Nehru

Question 4.
(a) Centralized planning – Planning from above
(b) Indicative planning – Mixed economies
(c) Imperative planning – China and Russia
(d) Totalitarian planning – Inducement planning
Answer:
(d) Totalitarian planning – Inducement planning

Question 5.
(a) Financial planning – Technique of planning
(b) NITI Aayog – Union cabinet resolution
(c) Seven pillars of effective governance – NITT
(d) Physical planning – Techniques of planning
Answer:
(c) Seven pillars of effective governance – NITT

VI. Pick The Odd One Out.

Question 1.
Economic development
(a) State of development
(b) Nature and level of change
(c) Scope of change
(d) Growth change
Answer:
(d) Growth change

Question 2.
Economic factors
(a) Natural resource
(b) Capital formation
(c) Size of the market
(d) Social change
Answer:
(d) Social change

Question 3.
Non – Economic factors
(a) Human resource
(b) Technical know-how
(c) Foreign trade
(d) Political freedom
Answer:
(c) Foreign trade

Question 4.
UDC characteristics are
(a) Low Per Capita Income
(b) Widespread poverty
(c) Low population
(d) Low rate of capital formation
Answer:
(c) Low population

Question 5.
The economic planning is justified on the following grounds.
(a) To accelerate and strengthen market mechanism
(b) To remove unemployment
(c) To remove agriculture
(d) To achieve balanced development
Answer:
(c) To remove agriculture

VII. Assertion And Reason.

Question 1.
Assertion (A): The traditional approach defines development strictly in economic terms.
Reason (R): The increase in GNP is accompanied by decline in share of agriculture in output and employment.

Question 2.
Assertion (A): Economic development depends on economic, social, political and religious factors.
Reason (R): Economic development is determined by single factor.

Question 3.
Assertion (A): Social Indicators are normally referred to as basic and collective needs of the people.
Reason (R): The basic needs such as health, education, food, water, sanitation and housing facilities check social backwardness.

Question 4.
Assertion (A): Capital is a neccessary but a sufficient condition of progress.
Reason (R): Economic development has much to do with human endowments, social attitudes, political conditions and historical accidents.

Question 5.
Assertion (A): The countries which adopt free market mechanism [Laissez faire] enjoy better growth rate compared to controlled economies.
Reason (R): It may be true for some countries but not every country.

Part – B
Answer The Following Questions In One or Two Sentences.

Question 1.
Define “Traditional Approach”?
Answer:
Traditional Approach:

The traditional approach defines development strictly in economic terms.
The increase in GNP is accompanied by decline in share of agriculture in output and employment while those of manufacturing and service sectors increase.

Question 2.
What is the meaning of New Welfare oriented Approach?
Answer:
New Welfare oriented Approach:

During 1970s, economic development was redefined in terms of reduction of poverty, ‘inequality’ and unemployment within the context of a growing economy.
In this phase, ‘Redistribution with Growth’ became the popular slogan.

Question 3.
Write “UDC” characteristics?
Answer:
The UDCs are characterized by predominance of primary sector i.e. agriculture, low per capita income, widespread poverty, wide inequality in distribution of income and wealth, over population, low rate of capital formation, high rate of unemployment, technological backwardness, dualism etc.

Question 4.
What is the meaning of underdevelopment?
Answer:
Meaning of Underdevelopment:
The term underdevelopment refers to that state of an economy where levels of living of masses are extremely low due to very low levels of Percapita income, resulting from low levels of productivity and high growth rate of population.

Question 5.
Define “Financial system.”?
Answer:
Financial System:

Financial system implies the existence of an efficient and organized banking system in the country.
There should be an organized money market to facilitate easy availability of capital.

Question 6.
Define “FOREX”?
Answer:
Foreign Trade:

The country which enjoys favorable balance of trade and terms of trade is always developed.
It has huge forex reserves and stable exchange rate.

Question 7.
Write casino capitalism?
Answer:
Casino Capitalism:
If People spend larger propotion of their income and time on entertainment liquor and other illegal activities, productive activities may suffer, according to Thomas Piketty.

Question 8.
Define “Planning”?
Answer:

Planning is a technique, a means to an end being the realization of certain pre-determined and well-defined aims and objectives laid down by a central planning authority.
The end may be to achieve economic, social, political or military objectives.

Question 9.
Define “Sarvodaya plan”?
Answer:
“Sarvodaya Plan” which was inspired by Gandhian Plan and with the idea of Vinoba Bhave.
It gave importance not only for agriculture, but encouraged small and cottage industries in the plan.

Question 10.
Write Gandhian plan and Bombay plan?
Answer:

S.N Agarwal (1944) gave the “Gandhian Plan” focusing on the agricultural and rural economy.
Bombay Plan (1940): The 8 leading industrialists of Bombay presented “Bombay Plan”. It was a 15 Year Investment Plan.

Part – C
Answer The Following Questions In One Paragraph.

Question 1.
Briefly explain Measurement of Economic Development?
Answer:
Measurement of Economic Development:
Economic development is measured on the basis of four criteria

(I) Gross National Product (GNP):
1. GNP is the total market value of all final goods and services produced within a nation in a particular year, plus income earned by its citizens (including income of those located abroad), minus income of non-residents located in that country.

2. GNP is one measure of the economic condition of a country, under the assumption that a higher GNP leads to a higher quality of living, all other things being equal.

(II) GNP per capita:

This relates to increase in the per capita real income of the economy over the long period.
This indicator of economic growth emphasizes that for economic development the rate of increase in real per capita income should be higher than the growth rate of population.

(III) Welfare:

Economic development is regarded as a process whereby there is an increase in the consumption of goods and services by individuals.
From the welfare perspective, economic development is defined as a sustained improvement in health, literacy and standard of living.

(IV) Social Indicators:

Social indicators are normally referred to as basic and collective needs of the people.
The direct provision of basic needs such as health, education, food, water, sanitation and housing facilities check social backwardness.

Question 2.
Explain Economic growth changes?
Answer:
(I) State of Development:
Generally speaking, economic development refers to the problems of underdeveloped countries and economic growth to those of developed countries.

(II) Nature and Level of Change:
Development is a discontinuous and spontaneous change while growth is a gradual and steady change in the long run.

(III) Scope of Change:

Growth simply means more output.
But development refers to efficiency in production i.e. output per unit of input.
It also implies changes in composition of output and in allocation of resources, reduction of poverty, inequality and unemployment.

(IV) Extent of change:
Economic development (wider concept than economic growth) is taken to mean growth plus structural change.

Question 3.
Explain economic factors capital formation?
Answer:
Capital Formation:

Capital formation is the main key to economic growth.
Capital formation refers to the net addition to the existing stock of capital goods which are either tangible like plants and machinery or intangible like health, education and research.
Capital formation helps to increase productivity of labour and thereby production and income.
It facilitates adoption of advanced techniques of production.
It leads to better utilization of natural resources, industrialization and expansion of markets which are essential for economic progress.

Question 4.
What is Crony capitalism?
Answer:
Social Organization:

People show interest in the development activity only when they feel that the fruits of development will be fairly distributed.
Mass participation in development programs is a pre-condition for accelerating the development process.
Whenever the defective social organization allows some groups to appropriate the benefits of growth.
Majority of the poor people do not participate in the process of development.
This is called crony capitalism.

Question 5.
Write Development of Infrastructure?
Answer:
Development of Infrastructure:

The agriculture and industrial sectors cannot develop in the absence of economic and social overheads.
The building of canals, roads, railways, power stations, etc., is indispensable for agricultural and industrial development.
Infrastructure involves huge capital investment long gestation period and low rate of return.
The state alone can provide strong infrastructural bases through planning.

Question 6.
Explain Price mechanism?
Answer:

Price mechanism provides for the automatic adjustment among price, demand and supply in a Laissez Faire economy.
The producers and consumers adjust their supply and demand based on price changes.
There is no such mechanism in a planned economy.
Advance calculations in a precise manner are impossible to make decisions regarding the consumption and production.
It is also very difficult to put the calculations into practice under planning.
Excess supply and excess demand can also happen in the market oriented economy.
Infact it has happened in many expitalistic economies, including the US.

Part – D
Answer The Following Questions In About A Page.

Question 1.
Explain the Economic planning in India?
Answer:
Economic Planning in India:

Consists of economic decisions, schemes formed to meet certain pre-determined economic objectives and a road map of directions to achieve specific goals within specific period of time.
The idea of economic planning was strengthened during the Great Depression in 1930s.
The outbreak of the World War II also required adequate and suitable planning of economic resources for the effective management after the effects of post war economy.
After Independence, in 1948, a declaration of industrial policy was announced.
The policy suggested the creation of a National Planning Commission and the elaboration of the policy of a mixed economic system.
On January 26, 1950, the Constitution came into force.
In logical order, the Planning Commission was created on March 15, 1950 and the plan era began on April 1, 1951 with the launch of the first five year plan (1951-56). The evolution of planning in India.

Question 2.
Explain the Human Resource of Economic Development?
Answer:
Human Resources:

Human resource is named as human capital because of its power to increase productivity and thereby national income.
There is a circular relationship between human development and economic growth.
A healthy, educated and skilled labour force is the most important productive asset.
Human capital formation is the process of increasing knowledge, skills and the productive capacity of people.
It includes expenditure on health, education and social services.
If labour is efficient and skilled, its capacity to contribute to growth will be high. For example Japan and China.

Question 3.
Discuss the Economic planning of Democratic planning and Totalitarian planning?
Answer:
Democratic Vs Totalitarian:
Samacheer Kalvi 12th Economics Solutions Chapter 11 Economics of Development and Planning

Democratic planning implies planning within democracy.
People are associated at every step in the formulation and implementation of the plan.
A democratic plan is characterized by the widest possible consultations with the various state governments and private enterprises at the stage of preparation.
The plan prepared by the Planning Commission is not accepted as such.
It can be accepted, rejected or modified by the Parliament of the country.
Under totalitarian planning, there is central control and direction of all economic activities in accordance with a single plan.
Consumption, production, exchange, and distribution are all controlled by the state. In authoritarian planning, the planning authority is the supreme body.
It decides about the targets, schemes, allocations, methods and procedures of implementation of the plan.

Question 4.
Briefly explain Indicative and Imperative planning?
Answer:
Indicative Vs Imperative Planning:

Indicative planning is peculiar to the mixed economies.
It has been in practice in France since the Monnet Plan of 1947-50.
In a mixed economy, the private sector and the public sector work together.
Under this plan, the outline of plan is prepared by the Government.
Then it is discussed with the representatives of private management, trade unions, consumer groups, finance institutions and other experts.
The essential function of planning is coordination of different economic units.
The state provides all types of facilities to the private sector.
The private sector is expected to fulfill the targets and priorities.
The state does not force the private sector but just indicate the areas of operation and targets to be fulfilled.
In short, the planning procedure is soft and flexible.
Under imperative planning, the state is all powerful in preparation and implementation of the plan.
Once a plan is drawn up, its implementation is a matter of enforcement.
The USSR President Stalin used to say, ‘Our plans are our instructions’.
There is complete control over the entire resources by the state.
There is no consumer sovereignty.
The Government policies and procedures are rigid.
China and Russia follow imperative planning.

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Samacheer Kalvi 12th Economics Solutions Chapter 5 Monetary Economics

April 24, 2024

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Tamilnadu Samacheer Kalvi 12th Economics Solutions Chapter 5 Monetary Economics

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Samacheer Kalvi 12th Economics Monetary Economics Text Book Back Questions and Answers

Part – A
Multiple Choice Questions.

Question 1.
The RBI Headquarters is located at ………………………
(a) Delhi
(b) Chennai
(c) Mumbai
(d) Bengalore
Answer:
(c) Mumbai

Question 2.
Money is ………………………
(a) Acceptable only when it has intrinsic value
(b) Constant in purchasing power
(c) The most liquid of all assets
(d) Needed for allocation of resources
Answer:
(c) The most liquid of all assets

Question 3.
Paper currency system is managed by the ………………………
(a) Central Monetary authority
(b) State Government
(c) Central Government
(d) Banks
Answer:
(a) Central Monetary authority

Question 4.
The basic distinction between M₁ and M₂ is with regard to ………………………
(a) Post office deposits
(b) Time deposits of banks
(c) Saving deposits of banks
(d) Currency
Answer:
(b) Time deposits of banks

Question 5.
Irving Fisher’s Quantity Theory of Money was popularized in ………………………
(a) 1908
(b) 1910
(c) 1911
(d) 1914
Answer:
(c) 1911

Question 6.
MV stands for ………………………
(a) Demand for money
(b) Supply of legal tender money
(c) Supply of bank money
(d) Total supply of money
Answer:
(b) Supply of legal tender money

Question 7.
Inflation means ………………………
(a) Prices are rising
(b) Prices are falling
(c) Value of money is increasing
(d) Prices are remaining the same
Answer:
(a) Prices are rising

Question 8.
………………………. inflation results in a serious depreciation of the value of money.
(a) Creeping
(b) Walking
(c) Running
(d) Hyper
Answer:
(d) Hyper

Question 9.
…………………… inflation occurs when general prices of commodities increases due to increase in production costs such as wages and raw materials.
(a) Cost – push
(b) Demand pull
(c) Running
(d) Galloping
Answer:
(a) Cost – push

Question 10.
During inflation, who are the gainers?
(a) Debtors
(b) Creditors
(c) Wage and salary earners
(d) Government
Answer:
(a) Debtors

Question 11.
…………………… is a decrease in the rate of inflation.
(a) Disinflation
(b) Deflation
(c) Stagflation
(d) Depression
Answer:
(a) Disinflation

Question 12.
Stagflation combines the rate of inflation with ……………………
(a) Stagnation
(b) Employment
(c) Output
(d) Price
Answer:
(a) Stagnation

Question 13.
The study of alternating fluctuations in business activity is referred to in Economics as ……………………
(a) Boom
(b) Recession
(c) Recovery
(d) Trade cycle
Answer:
(d) Trade cycle

Question 14.
During depression the level of economic activity becomes extremely ……………………
(a) High
(b) Bad
(c) Low
(d) Good
Answer:
(c) Low

Question 15.
“Money can be anything that is generally acceptable as a means of exchange and that the same time acts as a measure and a store of value”, This definition was given by ……………………
(a) Crowther
(b) A.C.Pigou
(c) F.A.Walker
(d) Francis Bacon
Answer:
(a) Crowther

Question 16.
Debit card is an example of ……………………
(a) Currency
(b) Paper currency
(c) Plastic money
(d) Money
Answer:
(c) Plastic money

Question 17.
Fisher’s Quantity Theory of money is based on the essential function of money as ……………………
(a) Measure of value
(b) Store of value
(c) Medium of exchange
(d) Standard of deferred payment
Answer:
(c) Medium of exchange

Question 18.
V in MV = PT equation stands for ……………………
(a) Volume of trade
(b) Velocity of circulation of money
(c) Volume of transaction
(d) Volume of bank and credit money
Answer:
(b) Velocity of circulation of money

Question 19.
When prices rise slowly, we call it ……………………
(a) Galloping inflation
(b) Mild inflation
(c) Hyper inflation
(d) Deflation
Answer:
(b) Mild inflation

Question 20.
…………………… inflation is in no way dangerous to the economy.
(a) Walking
(b) Running
(c) Creeping
(d) Galloping
Answer:
(c) Creeping

Part – B
Answer The Following Questions In One or Two Sentences.

Question 21.
Define Money?
Answer:

Many economists developed definition for money. Among these, definitions of Walker and Crowther are given below:
“Money is, what money does ” – Walker.
“Money can be anything that is generally acceptable as a means of exchange and at the same time acts as a measure and a store of value”. – Crowther
Money is anything that is generally accepted as payment for goods and services and repayment of debts and that serves as a medium of exchange.
A medium of exchange is anything that is widely accepted as a means of payments.

Question 22.
What is barter?
Answer:

Before money was invented, exchange took place by Barter, that is, commodities and services were directly exchanged for other commodities and services.
Such exchange of goods for goods was known as “Barter Exchange” or “Barter System”.

Question 23.
What is commodity money?
Answer:

After the barter system and commodity money system, modem money systems evolved.
Among these, metallic standard is the premier one. ,
Under metallic standard, some kind of metal either gold or silver is used to determine the standard value of the money and currency.
Standard coins made out of the metal are the principal coins used under the metallic standard.
These standard coins are full bodied or full weighted legal tender.
Their face value is equal to their intrinsic metal value.

Question 24.
What is gold standard?
Answer:

Gold Standard is a system in which the value of the monetary unit or the standard currency is directly linked with gold.
The monetary unit is defined in terms of a certain weight of gold.
The purchasing power of a unit of money is maintained equal to the value of a fixed weight of gold.

Question 25.
What is plastic money? Give example?
Answer:

The latest type of money is plastic money.
Plastic money is one of the most evolved forms of financial products.
Plastic money is an alternative to the cash or the standard “money”.
Plastic money is a term that is used predominantly in reference to the hard plastic cards used every day in place of actual bank notes.
Plastic money can come in many different forms such as Cash cards, Credit cards, Debit cards, Pre-paid Cash cards, Store cards, Forex cards and Smart cards.
They aim at removing the need for carrying cash to make transactions.

Question 26.
Define inflation?
Answer:

Inflation is a consistent and appreciable rise in the general price level.
In other words, inflation is the rate at which the general level of prices for goods and services is rising and consequently the purchasing power of currency is falling.
“Too much of Money chasing too few goods” – Coulbourn
“A state of abnormal increase in the quantity of purchasing power” – Gregorye

Question 27.
What is Stagflation?
Answer:
Stagflation is a combination of stagnant economic growth, high unemployment and high inflation.

Part – C
Answer The Following Questions In One Paragraph.

Question 28.
Write a note on metallic money?
Answer:

After the barter system and commodity money system, modem money systems evolved.
Among these, metallic standard is the premier one.
Under metallic standard, some kind of metal either gold or silver is used to determine the standard value of the money and currency.
Standard coins made out of the metal are the principal coins used under the metallic standard. Monetary Economics 93
These standard coins are full bodied or Ml weighted legal tender.
Their face value is equal to their intrinsic metal value.

Question 29.
What is money supply?
Answer:

Money supply means the total amount of money in an economy.
It refers to the amount of money which is in circulation in an economy at any given time.
Money supply plays a crucial role in the determination of price level and interest rates.
Money supply viewed at a given point of time is a stock and over a period of time it is a flow.

Question 30.
What are the determinants of money supply?
Answer:
Determinants of Money Supply:

Currency Deposit Ratio (CDR); It is the ratio of money held by the public in currency to that they hold in bank deposits.
Reserve deposit Ratio (RDR); Reserve Money consists of two things (a) vault cash in banks and (b) deposits of commercial banks with RBI.
Cash Reserve Ratio (CRR); It is the fraction of the deposits the banks must keep with RBI. (z’v) Statutory Liquidity Ratio (SLR); It is the fraction of the total demand and time deposits of the commercial banks is the form of specified liquid assests.

Question 31.
Write the types of inflation?
Answer:
The four types of inflation are –
1. Creeping Inflation:
Creeping inflation is slow-moving and very mild. The rise in prices will not be perceptible but spread over a long period. This type of inflation is in no way dangerous to the economy. This is also known as mild inflation or moderate inflation.

2. Walking Inflation:
When prices rise moderately and the annual inflation rate is a single digit . (3% – 9%), it is called walking or trolling inflation.

3. Running Inflation:
When prices rise rapidly like the running of a horse at a rate of speed of 10% – 20% per annum, it is called running inflation.

4. Galloping inflation:
Galloping inflation or hyper inflation points out to unmanageably high inflation rates that run into two or three digits. By high inflation the percentage of the same is almost 20%
to 100% from an overall perspective.

Other types of inflation (on the basis of inducement):

1. Currency inflation:
The excess supply of money in circulation causes rise in price level.

2. Credit inflation:
When banks are liberal in lending credit, the money supply increases and thereby rising prices. .

3. Deficit induced inflation:
The deficit budget is generally financed through printing of currency by the Central Bank. As a result, prices rise.

4. Profit induced inflation:
When the firms aim at higher profit, they fix the price with higher margin. So prices go up.

5. Scarcity induced inflation:
Scarcity of goods happens either due to fall in production (e.g. farm goods) or due to hoarding and black marketing. This also pushes up the price. (This has happened is Venezula in the year 2018).

6. Tax induced inflation:
Increase in indirect taxes like excise duty, custom duty and sales tax may lead to rise in price (e.g. petrol and diesel). This is also called taxflation.

Question 32.
Explain Demand-pull and Cost push inflation?
Answer:
Demand – Pull Vs Cost – Push inflation:

1. Demand – Pull Inflation:
Demand and supply play a crucial role in deciding the inflation levels in the society at all points of time. For instance, if the demand is high for a product and supply is low, the price of the products increases.

2. Cost – Push Inflation:
When the cost of raw materials and other inputsrises inflation results. Increase in wages paid to labour also leads to inflation.

Question 33.
State Cambridge equations of value of money?
Answer:
Cambridge Approach (Cash Balances Approach):

1. Marshall’s Equation:
The Marshall equation is expressed as:
M = KPY
Where
M is the quantity of money Y is the aggregate real income of the community . P is Purchasing Power of money
K represents the fraction of the real income which the public desires to hold in the form of money.
Thus, the price level P = M/KY or the value of money (The reciprocal of price level) is 1/P = KY/M
The value of money in terms of this equation can be found out by dividing the total quantity of goods which the public desires to holdout of the total income by the total supply of money. According to Marshall’s equation, the value of money is influenced not only by changes in M, but also by changes in K.

2. Keynes’Equation
Keynes equation is expressed as:
n = pk (or) p = n / k
Where
n is the total supply of money p is the general price level of consumption goods
k is the total quantity of consumption units the people decide to keep in the form of cash, Keynes indicates that K is a real balance, because it is measured in terms of consumer goods. According to Keynes, peoples’ desire to hold money is unaltered by monetary authority. So, price level and value of money can be stabilized through regulating quantity of money (n) by the monetary authority.
Later, Keynes extended his equation in the following form:
n = p (k + rk’) or p = n / (k + rk’)
Where,
n = total money supply p = price level of consumer goods
k = peoples’ desire to hold money in hand (in terms of consumer goods) in the total income of them
r = cash reserve ratio
k’ = community’s total money deposit in banks, in terms of consumers goods.
In this extended equation also, Keynes assumes that, k, k’ and r are constant. In this situation, price level (P) is changed directly and proportionately changing in money volume (n).

Question 34.
Explain disinflation?
Answer:
Disinflation:
Disinflation is the slowing down the rate of inflation by controlling the amount of credit (bank loan, hire purchase) available to consumers without causing more unemployment. Disinflation may be defined as the process of reversing inflation without creating unemployment or reducing output in the economy.

Part – D
Answer the following questions in one page.

Question 35.
Illustrate Fisher’s Quantity theory of money?
Answer:
(a) Fisher’s Quantity Theory of Money:
The quantity theory of money is a very old the¬ory. It was first propounded in 1588 by an Italian economist, Davanzatti. But, the credit for popularizing this theory in recent years rightly belongs to the well-known American economist, Irving Fisher who published his book, ‘The Purchasing Power of Money” in 1911. He gave it a quantitative form in terms of his famous “Equation of Exchange”.
The general form of equation given by Fisher is –
MV = PT

1. Fisher points out that in a country during any given period of time, the total quantity of money (MV) will be equal to the total value of all goods and services bought and sold (PT). MV = PT
Supply of Money = Demand for Money

2. This equation is referred to as “Cash Transaction Equation”.
Where M = Money Supply/quantity of Money
V = Velocity of Money
P = Price level
T = Volume of Transaction.
It is expressed as P = MV / T which implies that the quantity of money determines the price level and the price level in its turn varies directly with the quantity of money, provided ‘V’ and ‘T’ remain constant.

3. According to Marshall, peoples desire to hold money (the coefficient, K) is more powerful in determination of money, rather than quantity of money (M). So, peoples’ desire to hold money is a determinant of value of money.

4. The above equation considers only currency money. But, in a modem economy, bank’s demand deposits or credit money and its velocity play a vital part in business. Therefore, Fisher extended his original equation of exchange to include bank deposits M, and its velocity Vr The revised equation was:
PT = MV + M₁V₁
P = $\frac { MV+M_{ 1 }V_{ 1 } }{ T } $

5. From the revised equation, it is evident, that the price level is determined by (a) the quantity of money in circulation ‘M’ (b) the velocity of circulation of money ‘V’ (c) the volume of bank credit money M₁ (d) the velocity of circulation of credit money V₁, and the volume of trade (T)

Diagramatic Illustration:
Samacheer Kalvi 12th Economics Chapter 5 Monetary Economics

Quantity of Money

1. Figure (A) shows the effect of changes in the quantity of money on the price level. When the quantity of money is OM, the price level is OP. When the quantity of money is doubled to OM₂, the price level is also doubled to OP₂. Further, when the quantity of money is increased four – fold to OM₄, the price level also increases by four times to OP₄. This relationship is expressed by the curve OP = f (M) from the origin at 45°.

2. Figure (B), shows the inverse relation between the quantity of money and the value of money, where the value of money is taken on the vertical axis. When the quantity of money is OM₁, the value of money is 01 / P₁. But with the doubling of the quantity of money to OM₂, the value of money becomes one – half of what it was before, (01 / P₂). But, with the quantity of money increasing by four – fold to OM₄, the value of money is reduced by 01 / P₄. This inverse relationship between the quantity of money and the value of money is shown by downward sloping curve 1 / OP = f (M).

Question 36.
Explain the functions of money?
Answer:
Samacheer Kalvi 12th Economics Solutions Chapter 5 Monetary Economics

1. Primary Functions:

(I) Money as a medium of exchange:
This is considered as the basic function of money. Money has the quality of general acceptability, and all exchanges take place in terms of money.

(II) Money as a measure of value:
The second important function of money is that it measures the value of goods and services. In other words, the prices of all goods and services are expressed in terms of money. Money is thus looked upon as a collective measure of value.

2. Secondary Functions:

(I) Money as a Store of value:
Savings done in terms of commodities were not permanent. But, with the invention of money, this difficulty has now disappeared and savings are now done in terms of money. Money also serves as an excellent store of wealth, as it can be easily converted into other marketable assets, such as, land, machinery, plant etc.

(II) Money as a Standard of Deferred Payments:
Borrowing and lending were difficult problems under the barter system. In the absence of money, the borrowed amount could be returned only in terms of goods and services. But the modem money – economy has greatly facilitated the borrowing and lending processes.

(III) Money as a Means of Transferring Purchasing Power:
The field of exchange also went on extending with growing economic development. The exchange of goods is now extended to distant lands.

3. Contingent Functions:

(I) Basis of the Credit System:
Money is the basis of the Credit System. Business transactions are either in cash or on credit.

(II) Money facilitates distribution of National Income:
The task of distribution of national income was exceedingly complex under the barter system.

(III) Money helps to Equalize Marginal Utilities and Marginal Productivities:
Consumer can obtain maximum utility only if he incurs expenditure on various commodities in such a manner as to equalize marginal utilities accruing from them. Now in equalizing these marginal utilities, money plays an important role, because the prices of all commodities are expressed in money.

(IV) Money Increases Productivity of Capital:
Money is the most liquid form of capital. In other words, capital in the form of money can be put to any use.

4. Other Functions:

(I) Money helps to maintain Repayment Capacity:
Money possesses the quality of general acceptability. To maintain its repayment capacity, every firm has to keep assets in the form of liquid cash. The firm ensures its repayment capacity with money.

(II) Money represents Generalized Purchasing Power:
Purchasing power kept in terms of money can be put to any use. It is not necessary that money should be used only for the purpose for which it has been served.

(III) Money gives liquidity to Capital:
Money is the most liquid form of capital. It can be put to any use.

Question 37.
What are the causes and effects of inflation on the economy?
Answer:
Causes of Inflation:
The main causes of inflation in India are as follows:

1. Increase in Money Supply:
Inflation is caused by an increase in the supply of money which leads to increase in aggregate demand. The higher the growth rate of the nominal money supply, the higher is the rate of inflation.

2. Increase in Disposable Income:
When the disposable income of the people increases, it raises their demand for goods and services. Disposable income may increase with the rise in national income or reduction in taxes or reduction in the saving of the people.

3. Increase in Pubiic Expenditure:
Government activities have been expanding due to developmental activities and social welfare programmes. This is also a cause for price rise.

4. Increase in Consumer Spending:
The demand for goods and services increases when they are given credit to buy goods on hire-purchase and installment basis.

5. Cheap Monetary Policy:
Cheap monetary policy or the policy of credit expansion also leads to increase in the money supply which raises the demand for goods and services in the economy.

6. Deficit Financing:
In order to meet its mounting expenses, the government resorts to deficit financing by borrowing from the public and even by printing more notes.

7. Black Assests, Activities and Money:
The existence of black money and black assests due to corruption, tax evasion etc., increase the aggregate demand. People spend such money, lavishly. Black marketing and hoarding reduces the supply of goods.

8. Repayment of Public Debt:
Whenever the government repays its past internal debt to the public, it leads to increase in the money supply with the public.

9. Increase in Exports:
When exports are encouraged, domestic supply of goods decline. So prices rise.

Effects of Inflation:
The effects of inflation can be classified into two heads:

Effects on Production and
Effects on Distribution.

1. Effects on Production:
When the inflation is very moderate, it acts as an incentive to traders and producers. This is particularly prior to full employment when resources are not fully utilized. The profit due to rising prices encourages and induces business class to increase their investments in production, leading to generation of employment and income.

(I) However, hyper – inflation results in a serious depreciation of the value of money.

(II) When the value of money undergoes considerable depreciation, this may even drain out the foreign capital already invested in the country.

(III) With reduced capital accumulation, the investment will suffer a serious set-back which may have an adverse effect on the volume of production in the country.

(IV) Inflation also leads to hoarding of essential goods both by the traders as well as the consumers and thus leading to still hiher inflation rate.

(V) Inflation encourages investment in speculative activities rather than productive purposes.

2. Effects on Distribution:

1. Debtors and Creditors:
During inflation, debtors are the gainers while the creditors are losers.

2. Fixed – income Groups:
The fixed income groups are the worst hit during inflation because their incomes being fixed do not bear any relationship with the rising cost of living.

3. Entrepreneurs:
Inflation is the boon to the entrepreneurs whether they are manufacturers, traders, merchants or businessmen, because it serves as a tonic for business enterprise.

4. Investors:
The investors, who generally invest in fixed interest yielding bonds and securities have much to lose during inflation.

Question 38.
Describe the phases of Trade cycle?
Answer:
Phases of Trade Cycle
The four different phases of trade cycle is referred to as

Boom
Recession
Depression and
Recovery. These are illustrated in the figure:

Phases of Trade Cycle:

1. Boom or Prosperity Phase:
The full employment and the movement of the economy beyond full employment is characterized as boom period.

During this period, there is hectic activity in economy.
Money wages rise, profits increase and interest rates go up.
The demand for bank credit increases and there is all – round optimism.

Samacheer Kalvi 12th Economics Solutions Chapter 5 Monetary Economics

2. Recession:

The turning point from boom condition is called recession.
This happens at higher rate, than what was earlier.
Generally, the failure of a company or bank bursts the boom and brings a phase of recession.
Investments are drastically reduced, production comes down and income and profits decline.
There is panic in the stock market and business activities show signs of dullness.
Liquidity preference of the people rises and money market becomes tight.

3. Depression:

During depression the level of economic activity becomes extremely low.
Firms incur losses and closure of business becomes a common feature and the ultimate result is unemployment.
Interest prices, profits and wages are low. The agricultural class and wage earners would be worst hit.
Banking institutions will be reluctant to advance loans to businessmen.
Depression is the worst phase of the business cycle.
Extreme point of depression is called as “trough”, because it is a deep point in business cycle.

4. Recovery:

After a period of depression, recovery sets in.
This is the turning point from depression to revival towards upswing.
It begins with the revival of demand for capital goods.
Autonomous investments boost the activity.
The demand slowly picks up and in due course the activity is directed towards the upswing with more production, profit, income, wages and employment.
Recovery may be initiated by innovation or investment or by government expenditure (autonomous investment).

Samacheer Kalvi 12th Economics Consumption and Investment Functions Additional Questions

Part – A
I. Multiple Choice Questions.

Question 1.
During Inflation?
(a) Business men gain
(b) Wage earners gain
(c) Salary gain
(d) Renters gain
Answer:
(a) Business men gain

Question 2.
Galloping Inflation is also known as –
(a) Deflation
(b) Persistent Inflation
(c) Stagflation
(d) Cost – push Inflation
Answer:
(b) Persistent Inflation

Question 3.
The modem economy is described as –
(a) Demand Economy
(b) Supply Economy
(c) Money Economy
(d) Wage Economy
Answer:
(c) Money Economy

Question 4.
The term ………………………… refers to a phase or policy when interest rates are high.
(a) Purchasing money
(b) Power money
(c) Fiat money
(d) Dear money
Answer:
(d) Dear money

Question 5.
Currency notes in circulation are referred to as –
(b) Fiat money
(c) Value of money
(d) Cheap money
Answer:
(b) Fiat money

Question 6.
What is the name of inflation without a rise in price level?
(a) Repressed Inflation
(b) Hyper Inflation
(c) Galloping Inflation
(d) Cost – Push Inflation
Answer:
(a) Repressed Inflation

Question 7.
Give the example of a country that experienced hyper Inflation?
(a) India
(b) China
(c) Germany
(d) Africa
Answer:
(c) Germany

Question 8.
Which is the most important function of money?
(a) Measure of value
(b) Store of value
(c) Medium of exchange
(d) Standard of deferred payments
Answer:
(c) Medium of exchange

Question 9.
What is the other name for “Equation of Exchange”?
(a) Fisher’s Equation
(b) Keynes Equation
(c) Marshall’s Equation
(d) Equation of Exchange
Answer:
(a) Fisher’s Equation

Question 10.
What is the cheap money policy?
(a) High rates of Interest
(b) Low rates of Interest
(c) Medium rates of Interest
(d) Very high rates of Interest
Answer:
(b) Low rates of Interest

Question 11.
Monetary policy is controlled by –
(a) Central bank
(b) State Government
(c) Private sector
(d) Central Government
Answer:
(d) Central Government

Question 12.
………………………… is usually effective for controlling inflation.
(a) Monetary policy
(b) RBI
(c) State Government
(d) Central government
Answer:
(a) Monetary policy

Question 13.
Monetary policy is usually effective in controlling –
(a) Bank
(b) Inflation
(c) Deflation
(d) Stagflation
Answer:
(b) Inflation

Question 14.
Money acts as a common measure of –
(a) Reserve money
(b) Fiat money
(c) Value
(d) Broad money
Answer:
(c) Value

Question 15.
Bank rate is lowered during –
(a) Inflation
(b) Price
(c) Employment
(d) Deflation
Answer:
(d) Deflation

Question 16.
Under dear money policy is –
(a) Rate of Interest is low
(b) Rate of interest is high
(c) Bank rate is high
(d) Money supply is more
Answer:
(b) Rate of interest is high

Question 17.
M₃ is called –
(a) Narrow money
(b) Reserve money
(c) Broad money
(d) Fiat money
Answer:
(c) Broad money

Question 18.
Price mechanism plays a vital role in –
(a) Capitalism
(b) Socialism
(c) Mixed economy
(d) Traditional economy
Answer:
(a) Capitalism

Question 19.
“Money is what money does” ………………………… this definition was given by –
(a) Crowther
(b) Fisher
(c) Grasham
(d) Walker
Answer:
(d) Walker

Question 20.
Currency with the public is known as –
(a) M₁
(b) M₂
(C) M₃
(d) M₄
Answer:
(a) M₁

Question 21.
Cost – push inflation is induced by rising –
(a) Costs
(b) Money
(c) Broad money
(d) Inflation
Answer:
(b) Money

Question 22.
The direct exchange of goods for goods is known as –
(a) Money exchange
(b) Money transfer
(c) Barter System
(d) Barter goods
Answer:
(c) Barter System

Question 23.
Money is a matter of functions –
(a) One
(b) Two
(c) Three
(d) Four
Answer:
(d) Four

Question 24.
Deflation is a period marked by ………………………… prices.
(a) Increasing
(b) Falling
(c) Constant
(d) High
Answer:
(d) High

Question 25.
Dear money refers to ………………………… rate being high.
(a) Money
(b) Finance
(c) Interest
(d) Cost
Answer:
(c) Interest

II. Match the following and choose the correct answer by using codes given below

A. Deficit financing – (i) Monetary policy objectives
B. Store of value – (ii) Currency notes
C. Price stability – (iii) Causes inflation
D. Fiat money – (iv) Function of money
Codes:
(a) A (iii) B (iv) C (i) D (ii)
(b) A (ii) B (iii) C (iv) D (i)
(c) A (iv) B (ii) C (iii) D (i)
(d) A (i) B (iv) C (ii) D (iii)
Answer:
(a) A (iii) B (iv) C (i) D (ii)

Question 2.
A. Falling prices – (i) Black money
B. Government securities – (ii) Business loss
C. Bank rate – (iii) Open Market operation
D. Unaccounted money – (iv) Credit control
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (ii) B (iii) C (iv) D (i)
(c) A (iii) B (iv) C (i) D (ii)
(d) A (iv) B (i) C (ii) D (iii)
Answer:
(b) A (ii) B (iii) C (iv) D (i)

Question 3.
A. Checking Inflation – (i) Irving Fisher
B. Great Depression – (ii) Narrow money
C. Quantity theory of money – (iii) Wage freeze
D. M₁ – 1930
Codes:
(a) A (i) B (ii) C (iii) D (iv)
(b) A (iii) B (iv) C(i) D (ii)
(c) A (ii) B (iii) C (iv) D (i)
(d) A (iv) B (i) C (ii) D (iii)
Answer:
(b) A (iii) B (iv) C(i) D (ii)

Question 4.
A. Cheap money policy – (i) Purchasing money
B. Prices pushed – (ii) Creeping inflation
C. Value of money – (iii) Low rate of interest
D. Selective credit control – (iv) Moral suasion
Codes:
(a) A (iii) B (ii) C (i) D (iv)
(b) A (ii) B (i) C (iv) D (iii)
(c) A (iv) B (iii) C (ii) D (i)
(d) A (i) B (iv) C (iii) D (ii)
Answer:
(a) A (iii) B (ii) C (i) D (iv)

Question 5.
A. Galloping Inflation – (i) Money Act
B. M₃is called – (ii) Hyperinflation
C. Measure of value – (iii) Broad money
D. Deflation Codes – (iv) Bank rate
Codes:
(a) A (i) B (ii) C (iv) D (iii)
(b) A (iv) B (i) C (iii) D (ii)
(c) A (iii) B (iv) C (ii) D (i)
(d) A (ii) B (iii) C (i) D (iv)
Answer:
(d) A (ii) B (iii) C (i) D (iv)

III. State whether the statements are true or false.

Question 1.
(i) Inflation is taxation without legislation was said by Milton Friedman.
(ii) Money is the most liquid form of capital.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(a) Both (i) and (ii) are true

Question 2.
(i) “The purchasing power of money” was a book published by Irving Fisher in 1911.
(ii) The general form of equation given by Fisher is M = KPY.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(c) (i) is true but (ii) is false

Question 3.
(i) The study of alternating fluctuations in business activity is referred to in Economics as Trade cycle.
(ii) During depression the level of economic activity becomes extremely high.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(c) (i) is true but (ii) is false

Question 4.
(i) Creeping Inflation is in no way dangerous to the economy.
(ii) Debit card is an example of paper currency.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(c) (i) is true but (ii) is false

Question 5.
(i) MV = PT equation stands for volume of Trade.
(ii) Fisher’s Quantity Theory of money is based on the essential function of money as measure of value.

(a) Both (i) and (ii) are true
(b) Both (i) and (ii) are false
(c) (i) is true but (ii) is false
(d) (i) is false but (ii) is true
Answer:
(b) Both (i) and (ii) are false

IV. Which of the following is correctly matched:

Question 1.
(a) Medium of exchange – CRR
(b) Cash Reserve Ratio – Gold standard
(c) Goods exchange for goods – Barter system
(d) Full weighted legal tender – Plastic money
Answer:
(c) Goods exchange for goods – Barter system

Question 2.
(a) Depression – Starting stage
(b) Recession – Turning point from boom
(c) Boom – Economic activities
(d) Inflation – Hectic activity
Answer:
(b) Recession – Turning point from boom

Question 3.
(a) Store of value – Liquidity cash
(b) Deflation – Rise in price
(c) Trade cycle – Narrow money
(d) Quantity theory of money – J.M. Keynes
Answer:
(d) Quantity theory of money – J.M. Keynes

Question 4.
(a) The purchasing power of currency – Falling
(b) Monetary measures are adopted by – State bank
(c) The turning point from boom is – Inflation
(d) Money supply means the total – Inflation amount of money in – World
Answer:
(a) The purchasing power of currency – Falling

Question 5.
(a) The Marshall’s equation – MV = PT
(b) Cash Reserve Ratio – CRR
(c) Statutory Liquidity cash – SLC
(d) Functions of money – Money supply
Answer:
(b) Cash Reserve Ratio – CRR

Question 6.
(a) Barter System – Technology
(b) Gold Standard – Standard currency is directly linked with gold
(c) Plastic money – Money value
(d) Paper money – Smart card
Answer:
(b) Gold Standard – Standard currency is directly linked with gold

V. Which of the following is not correctly matched:

Question 1.
(a) Inflation – Rise in price
(b) Deflation – Fall in price
(c) Hyper Inflation – India
(d) Hyper deflation – Phases of Trade cycle
Answer:
(c) Hyper Inflation – India

Question 2.
(a) Currency Deposit Ratio – CDR
(b) Reserve Deposit Ratio – RDR
(c) Cash Reserve Ratio – CRR
(d) Statutory Liquidity Ratio – SRL
Answer:
(d) Statutory Liquidity Ratio – SRL

Question 3.
(a) M – Money supply / Quantity of money –
(b) V – Velocitu of money
(c) P – Price level
(d) T – Price rise slow moving
Answer:
(d) T – Price rise slow moving

Question 4.
(a) Creeping Inflation – Price rise slow moving
(b) Walking Inflation – Price rise moderately
(c) Running Inflation – Price rise rapidly running
(d) Galloping Inflation – Price rise very slow
Answer:
(d) Galloping Inflation – Price rise very slow

Question 5.
(a) Money supply – Central Bank
(b) Dear money policy – During Inflation
(c) Value of money – Purchasing power
(d) Black money – Narrow money
Answer:
(d) Black money – Narrow money

VI. Pick the odd one out.

Question 1.
The main functions of money can be classified
(a) Primary functions
(b) Secondary functions
(c) Contingent functions
(d) Territory functions
Answer:
(d) Territory functions

Question 2.
Money secondary functions are
(a) Money as a store of value
(b) Money as a standard of Deferred payments
(c) Money as a means of Transferring purchasing power
(d) Money as a modem exchange system
Answer:
(d) Money as a modem exchange system

Question 3.
Contingent functions are called
(a) Basis of the credit system
(b) Money facilitates distribution of state income
(c) Money’helps to equalize marginal utility
(d) Money increases productivity of capital
Answer:
(b) Money facilitates distribution of state income

Question 4.
RBI publishes information of money supply are
(a) M₂ = Currency coins and demand deposits
(b) M₂ = M₁ + Saving deposits with post office savings banks and Total Deposits
(c) M₃ = M₂ + Time deposits of all commercial and co – operative banks
(d) M₄ = M₃ + Total deposits with post offices
Answer:
(b) M₂ = M₁ + Saving deposits with post office savings banks and Total Deposits

Question 5.
Determinants of money supply are
(a) Consumer Deposit Ratio (CDR)
(b) Reserve Deposit Ratio (RDR)
(c) Cash Reserve Ratio (CRR)
(d) Statutory Liquidity Ratio (SLR)
Answer:
(a) Consumer Deposit Ratio (CDR)

Question 6.
Types of Inflation are
(a) Currency Inflation
(b) Credit Inflation
(c) Demand Induced Inflation
(d) Profit Induced Inflation
Answer:
(c) Demand Induced Inflation

Question 7.
The four different phases of trade cycle is referred to as
(a) Regression
(b) Recession
(c) Depression
(d) Recovery
Answer:
(a) Regression

VII. Assertion and Reason.

Question 1.
Assertion (A): Stagflation is a combination of stagnant economic growth, high unemployment and high inflation.
Reason (R): Stagflation is the slowing down the rate of inflation by controlling the amount of credit.

Question 2.
Assertion (A): Keynes and Milton Friedman together suggested Monetary measures, Fiscal measures and other measures to prevent and control of inflation.
Reason (R): Keynes and Milton Friedman together suggested other measures are Short term and Long – term measures.

Question 3.
Assertion (A): A trade cycle refers to oscillations in aggregate economic activity particularly in employment, output, income, etc.
Reason (R): The four different phases of trade cycle is referred to Boom, Recession, Depression and Recovery.

Question 4.
Assertion (A): Fiscal policy is now recognized as an important instrument to tackle an inflationary situation.
Reason (R): Monetary measures are adopted by the central bank.

Question 5.
Assertion (A): Currency is created by the RBI and Union Government.
Reason (R): Bank deposits are created by commercial banks and co-operative banks.

Question 6.
Assertion (A): Recovery may be initiated by Money balance.
Reason (R): Recovery may be government expenditure.

Part – B
Answer The Following Questions In One or Two Sentences.

Question 1.
Define “Silver Standard”?
Answer:
Silver Standard: The silver standard is a monetary system in which the standard economic unit of account is a fixed weight of silver. The silver standard is a monetary arrangement in which a country’s Government allows conversion of its currency into fixed amount of silver.

Question 2.
What is paper currency?
Answer:

The paper currency standard refers to the monetary system in which the paper currency notes issued by the Treasury or the Central Bank or both circulate as unlimited legal tender.
The paper standard is also known as managed currency standard.
The quantity of money in circulation is controlled by the monetary authority to maintain price stability.

Question 3.
Name the main functions of money?
Answer:
Samacheer Kalvi 12th Economics Chapter 5 Monetary Economics

Question 4.
Write RBI publishes information alternative measures of money supply?
Answer:
RBI publishes information for four alternative measures of Money supply, namely M₂ , M₂ and M₃ and M₄
M₁ = Currency, coins and demand deposits
M₂ = M₁ + Savings deposits with post office savings banks
M₃ = M₂ + Time deposits of all commercial and cooperative banks.
M₄ = M₃ + Total deposits with Post offices.

Question 5.
Define “Currency symbol”?
Answer:
Currency Symbol ₹
The new symbol designed by D.Udaya Kumar, a post graduate of IIT Bombay was finally selected by the Union cabinet on 15th July, 2010. The new symbol, is an amalgamation of Devanagri ‘Ra’ and the Roman ‘R’ without the stem. The symbol of India rupee came into use on 15th July, 2010. After America, Britain, Japan, Europe Union. India is the 5th country to accept a unique currency symbol.

Question 6.
Write Fisher’s Quantity Theory of money equation?
Answer:

The general form of equation given by Fisher is MV = PT.
Fisher points out that in a country during any given period of time, the total quantity of money (MV) will be equal to the total value of all goods and services bought and sold (PT).
MV = PT

Question 7.
Define “Trade cycle”?
Answer:
“A trade cycle is composed of periods of good trade characterised by rising prices and low unemployment percentages altering with periods of bad trade characterised by falling prices and high unemployment percentages”.

Part – C
Answer The Following Questions In One Paragraph.

Question 1.
Write the meaning of Money supply?
Answer:
Meaning of Money Supply

In India, currency notes are issued by the Reserve Bank of India (RBI) and coins are issued by the Ministry of Finance, Government of India (GOI).
Besides these, the balance is savings, or current account deposits, held by the public in commercial banks is also considered money.
The currency notes are also called fiat money and legal tenders.

Question 2.
Explain the Deflation?
Answer:
Deflation:

The essential feature of deflation is falling prices, reduced money supply and unemployment.
Though falling prices are desirable at the time of inflation, such a fall should not lead to the fall in the level of production and employment.
But if prices fall from the level of full employment both income and employment will be adversely affected.

Question 3.
What is the meaning of trade cycle?
Answer:
Meaning of Trade Cycle:

A Trade cycle refers to oscillations in aggregate economic activity particularly in employment, output, income, etc.
It is due to the inherent contraction and expansion of the elements which energize the economic activities of the nation.
The fluctuations are periodical, differing in intensity and changing in its coverage.

Question 4.
Explain the Evolution of money?
Answer:
Barter System:

The introduction of money as a medium of exchange was orje of the greatest inventions of mankind.
Before money was invented, exchange took place by Barter, that is, commodities and services were directly exchanged for other commodities and services.
Under the barter system, buyers and sellers of commodities had to face a number of difficulties.
Surplus goods were exchanged for money which in turn was exchanged for other needed goods.
Goods like furs, skins, salt, rice, wheat, utensils, weapons, etc. were commonly used as money.
Such exchange of goods for goods was known as “Barter Exchange” or “Barter System”.

Question 5.
What is the meaning of Crypto currency?
Answer:
Crypto Currency:

A digital currency in which encryption techniques are used to regulate the generation of units of currency and verify the transfer of funds, operating independently of a Central Bank.
Decentralised crypto currencies such as Bitcoin now provide an outlet for Personal Wealth that is beyond restriction and confiscation.

Question 6.
Explain the Trade cycle Depression?
Answer:
Depression:

During depression the level of economic activity becomes extremely low.
Firms incur losses and closure of business becomes a common feature and the ultimate result is unemployment.
Interest prices, profits and wages are low.
The agricultural class and wage earners would be worst hit.
Banking institutions will be reluctant to advance loans to businessmen.
Depression is the worst phase of the business cycle.
Extreme point of depression is called as “trough”, because it is a deep point in business cycle.
Any person fell down in deeps could not come out from that without other’s help.
Similarly, an economy fell down in trough could not come out from this without external help.
Keynes advocated that autonomous investment of the government alone can help the economy to come out from the depression.

Part – D
Answer The Following Questions In One Page.

Question 1.
Explain the Measures of control inflation?
Answer:
Measures to Control Inflation:
Keynes and Milton Friedman together suggested three measures to prevent and control of inflation.

Monetary measures
Fiscal measures (J.M. Keynes) and
Other measures.

1. Monetary Measures:

These measures are adopted by the Central Bank of the country.
They are
- Increase in Bankrate
- Sale of Government Securities in the Open Market
- Higher Cash Reserve Ratio (CRR) and Statutory Liquidity Ratio (SLR)
- Consumer Credit Control and
- Higher margin requirements
- Higher Repo Rate and Reverse Repo Rate.

2. Fiscal Measures:

Fiscal policy is now recognized as an important instrument to tackle an inflationary situation.
The major anti – inflationary fiscal measures are the following:
Reduction of Government Expenditure and Public Borrowing and Enhancing taxation.

3. Other Measures:
These measures can be divided broadly into short – term and long – term measures.

(a) Short – term measures can be in regard to public distribution of scarce essential commodities through fair price shops (Rationing). In India whenever shortage of basic goods has been felt, the government has resorted to import so that inflation may not get triggered.

(b) Long – term measures will require accelerating economic growth especially of the wage goods which have a direct bearing on the general price and the cost of living. Some restrictions on present consumption may help in improving saving and investment which may be necessary for accelerating the rate of economic growth in the long run.

Question 2.
Briefly explain the Monetary Economics and money?
Answer:

Monetary Economics is a branch of economics that provides a framework for analyzing money and its functions as a medium of exchange, store of value and unit of account.
It examines the effects of monetary systems including regulation of money and associated financial institutions.
Meaning
Money is anything that is generally accepted as payment for goods and services and repayment of debts and that serves as a medium of exchange.
A medium of exchange is anything that is widely accepted as a means of payments.
In recent years, the importance of credit has increased in all the countries of the world.
Credit instruments are used on an extensive scale.
The use of cheques, bills of exchange, etc. has gone up.
It should however, be remembered that money is the basis of credit.

Question 3.
Explain the Inflation Effects of production?
Answer:
Effects on Production: When the inflation is very moderate, it acts as an incentive to traders and producers. This is particularly prior to full employment when resources are not fully utilized. The profit due to rising prices encourages and induces business class to increase their investments in production, leading to generation of employment and income.

1. However, hyper – inflation results in a serious depreciation of the value of money and it discourages savings on the part of the public.

2. When the value of money undergoes considerable depreciation, this may even drain out the foreign capital already invested in the country.

3. With reduced capital accumulation, the investment will suffer a serious set – back which may have an adverse effect on the volume of production in the country. This may discourage entrepreneurs and business men from taking business risk.

4. Inflation also leads to hoarding of essential goods both by the traders as well as the consumers and thus leading to still higher inflation rate.

5. Inflation encourages investment in speculative activities rather than productive purposes.

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Samacheer Kalvi 12th Physics Solutions Chapter 11 Recent Developments in Physics

April 22, 2024

Students those who are preparing for the 12th Physics exam can download this Samacheer Kalvi 12th Physics Book Solutions Questions and Answers for Chapter 11 Recent Developments in Physics from here free of cost. These Tamilnadu State Board Solutions for Class 12th Physics PDF cover all Chapter 11 Recent Developments in Physics Questions and Answers. All these concepts of Samacheer Kalvi 12th Physics Book Solutions Questions and Answers are explained very conceptually as per the board prescribed Syllabus & guidelines.

Tamilnadu Samacheer Kalvi 12th Physics Solutions Chapter 11 Recent Developments in Physics

Kickstart your preparation by using this Tamilnadu State Board Solutions for 12th Physics Chapter 11 Recent Developments in Physics Questions and Answers and get the max score in the exams. You can cover all the topics of Chapter 11 Recent Developments in Physics Questions and Answers pdf. Download the Tamilnadu State Board Solutions by accessing the links provided here and ace up your preparation.

Samacheer Kalvi 12th Physics Recent Developments in Physics Textual Evaluation Solved

Samacheer Kalvi 12th Physics Recent Developments in Physics Multiple Choice Questions

Question 1.
The particle size of ZnO material is 30 nm. Based on the dimension it is classified as –
(a) Bulk material
(b) Nanomaterial
(c) Soft material
(d) Magnetic material.
Answer:
(b) Nanomaterial

Question 2.
Which one of the following is the natural nanomaterial?
(a) Peacock feather
(b) Peacock beak
(c) Grain of sand
(d) Skin of the Whale.
Answer:
(a) Peacock feather

Question 3.
The blue print for making ultra durable synthetic material is mimicked from-
(a) Lotus leaf
(b) Morpho butterfly
(c) Parrot fish
(d) Peacock feather.
Answer:
(c) Parrot fish

Question 4.
The method of making nanomaterial by assembling the atoms is called-
(a) Top down approach
(h) Bottom up approach
(c) Cross down approach
(d) Diagonal approach.
Answer:
(b) Bottom up approach

Question 5.
“Sky wax” is an application of nano product in the field of-
(a) Medicine
(b) Textile
(c) Sports
(d) Automotive industry.
Answer:
(c) Sports

Question 6.
The materials used in Robotics are-
(a) Aluminium and silver
(b) Silver and gold
(c) Copper and gold
(d) Steel and aluminium.
Answer:
(d) Steel and aluminum.

Question 7.
The alloys used for muscle wires in Robots are-
(a) Shape memory alloys
(b) Gold copper alloys
(c) Gold silver alloys
(d) Two dimensional alloys.
Answer:
(a) Shape memory alloys

Question 8.
The technology used for stopping the brain from processing pain is-
(a) Precision medicine
(b) Wireless brain sensor
(c) Virtual reality
(d) Radiology.
Answer:
(c) Virtual reality

Question 9.
The particle which gives mass to protons and neutrons are-
(a) Higgs particle
(b) Einstein particle
(c) Nanoparticle
(d) Bulk particle.
Answer:
(a) Higgs particle

Question 10.
The gravitational waves were theoretically proposed by-
(a) Conrad Rontgen
(b) Marie Curie
(c) Albert Einstein
(d) Edward Purcell.
Answer:
(c) Albert Einstein

Samacheer Kalvi 12th Physics Recent Developments in Physics Short Answer Questions

Question 1.
Distinguish between Nanoscience and Nanotechnology?
Answer:
1. Nanoscience:

Nanoscience is the science of objects with typical sizes of 1 – 100 nm. Nano means one – billionth of a metre that is 10^-9m.
If matter is divided into such small objects the mechanical, electrical, optical, magnetic and other properties change.

2. Nanotechnology:

Nanotechnology is a technology involving the design, production, characterization, and applications of nano structured materials.

Question 2.
What is the difference between Nano materials and Bulk materials?
Answer:

The solids are made up of particles. Each of the particle has a definite number of atoms, which might differ from material to material. If the particle of a solid is of size less than 100 nm, it is said to be a ‘nano solid’.
When the particle size exceeds 100 nm, it is a ‘bulk solid’. It is to be noted that nano and bulk solids may be of the same chemical composition.
For example, ZnO can be both in bulk and nano form.
Though chemical composition is the same, nano form of the material shows strikingly different properties when compared to its bulk counterpart.

Question 3.
Give any two examples for “Nano” in nature.
Answer:
1. Single strand DNA:
A single strand of DNA, the building block of all living things, is about three nanometers wide.

2. Morpho Butterfly:
The scales on the wings of a morpho butterfly contain nanostructures that change the way light waves interact with each other, giving the wings brilliant metallic blue and green hues. Mimic in laboratories – Manipulation of colours by adjusting the size of nano particles with which the materials are made.

Question 4.
Mention any two advantages and disadvantages of Robotics.
Answer:

Advantages of Robotics:
- The robots are much cheaper than humans.
- Robots never get tired like humans. It can work for 24 x 7. Hence absenteeism in work place can be reduced.
- Robots are more precise and error free in performing the task.
Disadvantages of Robotics:
- Robots have no sense of emotions or conscience.
- They lack empathy and hence create an emotionless workplace.
- If ultimately robots would do all the work, and the humans will just sit and monitor them, health hazards will increase rapidly.

Question 5.
Why steel is preferred in making Robots?
Answer:
Steel is several time stronger. In any case, because of the inherent strength of metal, robot bodies are made using sheet, bar, rod, channel, and other shapes.

Question 6.
What are black holes?
Answer:
Black holes are end stage of stars which are highly dense massive object. Its mass ranges from 20 times mass of the sun to 1 million times mass of the sun. It has very strong gravitational force such that no particle or even light can escape from it. The existence of black holes is studied when the stars orbiting the black hole behave differently from the other starts. Every galaxy has black hole at its center. Sagittarius A* is the black hole at the center of the Milky Way galaxy.

Question 7.
What are sub atomic particles?
Answer:

The three main subatomic particles that form an atom are protons, neutrons and electrons.
Subatomic particles are particles that are smaller than the atom, proton and neutron are made up of quarks which is interact through gluons.
Subatomic particle having two types of particles, they are elementary particle and composite particle.

Samacheer Kalvi 12th Physics Recent Developments in Physics Long Answer Questions

Question 1.
Discuss the applications of Nanomaterials in various fields?
Answer:
(i) Automotive industry:

Lightweight construction
Painting (fillers, base coat, clear coat)
Catalysts
Tires (fillers)
Sensors
Coatings for window screen and car bodies

(ii) Chemical industry:

Fillers for paint systems
Coating systems based on nanocomposites
Impregnation of papers
Switchable adhesives
Magnetic fluids

(iii) Engineering

Wear protection for tools and machines (anti blocking coatings, scratch resistant coatings on plastic parts, etc.)
Lubricant – free bearings

(iv) Electronic industry

Data memory
Displays
Laser diodes
Glass fibres
Optical switches
Filters (IR-blocking)
Conductive, antistatic coatings

(v) Construction:

Construction materials
Thermal insulation
Flame retardants
Surface – functionalised building materials for wood, floors, stone, facades, tiles, roof tiles, etc.
Facade coatings
Groove mortar

(vi) Medicine:

Drug delivery systems
Contrast medium
Prostheses and implants
Agents in cancer therapy
Active agents
Medical rapid tests
Antimicrobial agents and coatings

(vii) Textile / fabrics / non – wovens:

Surface – processed textiles
Smart clothes

(viii) Energy:

Fuel cells
Solar cells
Batteries
Capacitors

(ix) Cosmetics:

Sun protection
Lipsticks
Skin creams
Tooth paste

(x) Food and drinks:

Package materials
Additives
Storage life sensors
Clarification of fruit juices

(xi) Household:

Ceramic coatings for irons
Odors catalyst
Cleaner for glass, ceramic, floor, windows

(xii) Sports / outdoor:

Ski wax
Antifogging of glasses / goggles
Antifouling coatings for ships / boats
Reinforced tennis rackets and balls.

Question 2.
What are the possible harmful effects of usage of Nanoparticles? Why?
Answer:
Possible harmful effects of usage of Nanoparticles:

1. The research on the harmful impact of application of nanotechnology is also equally important and fast developing. The major concern here is that the nanoparticles have the dimensions same as that of the biological molecules such as proteins. They may easily get absorbed onto the surface of living organisms and they might enter the tissues and fluids of the body.

2. The adsorbing nature depends on the surface of the nanoparticle. Indeed, it is possible to deliver a drug directly to a specific cell in the body by designing the surface of a nanoparticle so that it adsorbs specifically onto the surface of the target cell.

3. The interaction with living systems is also affected by the dimensions of the nanoparticles. For instance, nanoparticles of a few nanometers size may reach well inside biomolecules, which is not possible for larger nanoparticles.

4. Nanoparticles can also cross cell membranes. It is also possible for the inhaled nanoparticles to reach the blood, to reach other sites such as the liver, heart or blood cells.

5. Researchers are trying to understand the response of living organisms to the presence of nanoparticles of varying size, shape, chemical composition and surface characteristics.

Question 3.
Discuss the functions of key components in Robots?
Answer:
The robotic system mainly consists of sensors, power supplies, control systems, manipulators and necessary software. Most robots are composed of 3 main parts:

1. The Controller: Also known as the “brain” which is run by a computer program. It gives commands for the moving parts to perform the job.
2. Mechanical parts: Motors, pistons, grippers, wheels, and gears that make the robot move, grab, turn, and lift.
3. Sensors: To tell the robot about its surroundings. It helps to determine the sizes and shapes of the objects around, distance between the objects, and directions as well.

Question 4.
Elaborate any two types of Robots with relevant examples?
Answer:
(i) Human Robot: Certain robots are made to resemble humans in appearance and replicate the human activities like walking, lifting, and sensing, etc.

Power conversion unit:
Robots are powered by batteries, solar power, and hydraulics.
Actuators:
Converts energy into movement. The majority of the actuators produce rotational or linear motion.
Electric motors:
They are used to actuate the parts of the robots like wheels, arms, fingers,
legs, sensors, camera, weapon systems etc. Different types of electric motors are used. The most often used ones are AC motor, Brushed DC motor, Brushless DC motor, Geared DC motor, etc.
Pneumatic Air Muscles:
They are devices that can contract and expand when air is pumped inside. It can replicate the function of a human muscle. They contract almost 40% when the air is sucked inside them.
Muscle wires:
They are thin strands of wire made of shape memory alloys. They can contract by 5% when electric current is passed through them.
Piezo Motors and Ultrasonic Motors:
Basically, we use it for industrial robots.
Sensors:
Generally used in task environments as it provides information of real – time knowledge.
Robot locomotion:
Provides the types of movements to a robot. The different types are:
- Legged
- Wheeled
- Combination of Legged and Wheeled Locomotion
- Tracked slip / skid.

(ii) Industrial Robots:
Six main types of industrial robots:

Cartesian
SCARA (Selective Compliance Assembly Robot Arm)
Cylindrical
Delta
Polar
Vertically articulated

Six – axis robots are ideal for:

Arc Welding
Spot Welding
Material Handling
Machine Tending
Other Applications

Question 5.
Comment on the recent advancement in medical diagnosis and therapy.
Answer:
The recent advancement in medical diagnosis and therapy:

Virtual reality
Precision medicine
Health wearables
Artificial organs
3 – D printing
Wireless brain sensors
Robotic surgery
Smart inhalers

1. Virtual reality:
Medical virtual reality is effectively used to stop the brain from processing pain and cure soreness in the hospitalized patients. Virtual reality has enhanced surgeries by the use of 3D models by surgeons to plan operations. It helps in the treatment of Autism, Memory loss, and Mental illness.

2. Precision medicine:
Precision medicine is an emerging approach for disease treatment and prevention that takes into account individual variability in genes, environment, and lifestyle for each person. In this medical model it is possible to customise healthcare, with medical decisions, treatments, practices, or products which are tailored to the individual patient.

3. Health wearables:
A health wearable is a device used for tracking a wearer’s vital signs or health and fitness related data, location, etc. Medical wearables with artificial intelligence and big data provide an added value to healthcare with a focus on diagnosis, treatment, patient monitoring and prevention.

Note: Big Data:Extremely large data sets that may be analysed computationally to reveal patterns, trends, and associations, especially relating to human behaviour and interactions.

4. Artificial organs:
An artificial organ is an engineered device or tissue that is implanted or integrated into a human. It is possible to interface it with living tissue or to replace a natural organ. It duplicates or augments a specific function or functions of human organs so that the patient may return to a normal life as soon as possible.

5. 3D printing:
Advanced 3D printer systems and materials assist physicians in a range of operations in the medical field from audiology, dentistry, orthopedics and other applications.

6. Wireless brain sensors:
Wireless brain sensors monitor intracranial pressure and temperature and then are
absorbed by the body. Hence there is no need for surgery to remove these devices.

7. Robotic surgery:
Robotic surgery is a type of surgical procedure that is done using robotic systems. Robotically – assisted surgery helps to overcome the limitations of pre – existing minimally invasive surgical procedures and to enhance the capabilities of surgeons performing open
surgery.

8. Smart inhalers:
Inhalers are the main treatment option for asthma. Smart inhalers are designed with health systems and patients in mind so that they can offer maximum benefit. Smart inhalers use bluetooth technology to detect inhaler use, remind patients when to take their medication and gather data to help guide care.

Samacheer Kalvi 12th Physics Recent Developments in Physics Additional Questions

Samacheer Kalvi 12th Physics Recent Developments in Physics Multiple Choice Questions

Question 1.
An automatic apparatus or device that performs functions ordinarily ascribed to human or
operate with what appears to be almost human intelligence is called ……………. .
(a) Robot
(b) Human
(c) Animals
(d) Reptiles.
Answer:
(a) Robot.

Question 2.
The laws of Robotics are ……………. .
(a) a robot may not injure a human being
(b) a robot must obey the order given by human
(c) a robot must protect its own existence
(d) both b and c.
Answer:
(d) both b and c.
Hint:
A robot may not injure a human being or through in action, allow human being to be harmed.

Question 3.
The basic components of robot are ……………. .
(a) mechanical linkage
(b) sensors and controllers
(c) user interface and power conversion unit
(d) All the above.
Answer:
(d) All the above.

Question 4.
What is the name for information sent from robot sensors to robot controllers ……………. .
(a) temperature
(b) pressure
(c) feedback
(d) signal.
Answer:
(c) feedback

Question 5.
Which of the following uses radio frequency to produce nano – particles ……………. .
(a) Plasma arching
(b) Chemical vapour deposition
(c) Sol-gel technique
(d) Electro deposition.
Answer:
(a) Plasma arching

Question 6.
Which of the following the atoms do not move from each other ……………. .
(a) Shape memory alloys
(b) Nano materials
(c) Dielectrics
(d) Static materials.
Answer:
(b) Nano materials

Question 7.
The diameter of the nano wire is about ……………. .
(a) 10^-6 m
(b) 10^-3 m
(c) 10^-8 m
(d) 10^-9 m.
Answer:
(d) 10^-9 m.

Question 8.
A suspended nano wire is a wire that is produced in ……………. .
(a) Air medium
(b) Vaccum
(c) Low vaccum chamber
(d) High vaccum chamber.
Answer:
(d) High vaccum chamber.

Question 9.
For nano metres whose diameters less than …………….are used as welding purposes.
(a) 10 nm
(b) 20 nm
(c) 30 nm
(d) 40 nm.
Answer:
(a) 10 nm

Question 10.
Nano wires are used in ……………. .
(a) 10 nm
(b) Resistors
(c) Capacitors
(d) Transducers.
Answer:
(a) 10 nm

Question 11.
Generally what is the material of needle electrodes ……………. .
(a) Stainless steel
(b) Copper
(c) Lead
(d) Iron.
Answer:
(a) Stainless steel

Question 12.
……………. introduced is used to hold patients head and guide the placements of electrodes.
(a) Monotaxic
(b) Stereotonic
(c) Stereotaxic
(d) Monotonic.
Answer:
(c) Stereotaxic

Question 13.
Who is the father of the modem robotics industry formed the world’s first robotic company in 1956 ……………. .
(a) Joliot
(b) Cormark
(c) Engelberger
(d) Edward purcell.
Answer:
(c) Engelberger

Question 14.
In 1954, ……………. invented the first digitally operated programmable robot called unimate.
(a) Edward purcell
(b) George Devol
(c) Engel berger
(d) Joliot.
Answer:
(b) George Devol

Question 15.
The phenomenon of artificial radioactivity was invented by ……………. .
(a) Joliot and Irene curie
(b) Felix Bloch and Edward purcell
(c ) Connack and Hounsfield
(d) Wilhelm conrad – Rontgen.
Answer:
(a) Joliot and Irene curie

Samacheer Kalvi 12th Physics Recent Developments in Physics Short Answer Question

Question 1.
What is physics?
Answer:
Physics is the basic building block for Science, Engineering, Technology and Medicine.

Question 2.
Write down the applications of Nano technology?
Answer:

Energy storage
Metallurgy and materials
Optical engineering and communication
Agriculture and food
Biotechnology
Defense and security Electronics
Biomedical and drug delivery
Cosmetics and paints
Textile.

Question 3.
What is robotics?
Answer:
Robotics is an integrated study of mechanical engineering, electronic engineering, computer engineering, and science.

Question 4.
What is meant by ‘Robot’? Write its uses?
Answer:
Robot is a mechanical device designed with electronic circuitry and programmed to perform a specific task. These automated machines are highly significant in this robotic era where they can take up the role of humans in certain dangerous environments that are hazardous to people like defusing bombs, finding survivors in unstable ruins, and exploring mines and shipwrecks.

Question 5.
What is the meaning of particle physics?
Answer:
Particle physics deals with the theory of fundamental particles of nature and it is one of the active research areas in physics. Initially it was thought that atom is the fundamental entity of matter.

Question 6.
Define cosmology?
Answer:
Cosmology is the branch that involves the origin and evolution of the universe. It deals with formation of stars, galaxy etc.

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Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics

April 22, 2024

Students those who are preparing for the 12th Physics exam can download this Samacheer Kalvi 12th Physics Book Solutions Questions and Answers for Chapter 9 Semiconductor Electronics from here free of cost. These Tamilnadu State Board Solutions for Class 12th Physics PDF cover all Chapter 9 Semiconductor Electronics Questions and Answers. All these concepts of Samacheer Kalvi 12th Physics Book Solutions Questions and Answers are explained very conceptually as per the board prescribed Syllabus & guidelines.

Tamilnadu Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics

Kickstart your preparation by using this Tamilnadu State Board Solutions for 12th Physics Chapter 9 Semiconductor Electronics Questions and Answers and get the max score in the exams. You can cover all the topics of Chapter 9 Semiconductor Electronics Questions and Answers pdf. Download the Tamilnadu State Board Solutions by accessing the links provided here and ace up your preparation.

Samacheer Kalvi 12th Physics Semiconductor Electronics Textual Evaluation Solved

Samacheer Kalvi 12th Physics Semiconductor Electronics Multiple Choice Questions

Question 1.
The barrier potential of a silicon diode is approximately,
(a) 0.7 V
(b) 0.3 V
(c) 2.0 V
(d) 2.2 V.
Answer:
(a) 0.7 V

Question 2.
Doping a semiconductor results in
(a) The decrease in mobile charge carriers
(b) The change in chemical properties
(c) The change in the crystal structure
(d) The breaking of the covalent bond.
Answer:
(c) The change in the crystal structure

Question 3.
A forward biased diode is treated as-
(a) An open switch with infinite resistance
(b) A closed switch with a voltage drop of 0V
(c) A closed switch in series with a battery voltage of 0.7V
(d) A closed switch in series with a small resistance and a battery.
Answer:
(d) A closed switch in series with a small resistance and a battery.

Question 4.
If a half – wave rectified voltage is fed to a load resistor, which part of a cycle the load current will flow?
(a) 0° – 90°
(b) 90° – 180°
(c) 0° – 180°
(d) 0° – 360°
Answer:
(c) 0° – 180°

Question 5.
The primary use of a zener diode is-
(a) Rectifier
(b) Amplifier
(c) Oscillator
(d) Voltage regulator.
Answer:
(d) Voltage regulator.

Question 6.
The principle in which a solar cell operates-
(a) Diffusion
(b) Recombination
(c) Photovoltaic action
(d) Carrier flow.
Answer:
(c) Photovoltaic action

Question 7.
The light emitted in an LED is due to-
(a) Recombination of charge carriers
(b) Reflection of light due to lens action
(c) Amplification of light falling at the junction.
Answer:
(a) Recombination of charge carriers

Question 8.
When a transistor is fully switched on, it is said to be-
(a) Shorted
(b) Saturated
(c) Cut – off
(d) Open.
Answer:
(b) Saturated

Question 9.
The specific characteristic of a common emitter amplifier is-
(a) High input resistance
(b) Low power gain
(c) Signal phase reversal
(d) Low current gain.
Answer:
(c) Signal phase reversal

Question 10.
To obtain sustained oscillation in an oscillator,
(a) Feedback should be positive
(b) Feedback factor must be unity
(c) Phase shift must be 0 or 2π
(d) All the above.
Answer:
(d) All the above.

Question 11.
If the input to the NOT gate is A = 1011, its output is?
(a) 0100
(b) 1000
(c) 1100
(d) 0011.
Answer:
(a) 0100

Question 12.
The electrical series circuit in digital form is-
(a) AND
(b) OR
(c) NOR
(d) NAND.
Answer:
(a) AND

Question 13.
Which one of the following represents forward bias diode? (NEET)
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-1
Answer:

Question 14.
The given electrical network is equivalent to (NEET)
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-3
(a) AND gate
(b) OR gate
(c) NOR gate 1
(d) NOT gate.
Answer:
(c) NOR gate

Question 15.
The output of the following circuit is 1 when the input ABC is (NEET 2016)
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-4
(a) 101
(b) 100
(c) 110
(d) 010.
Answer:
(a) 101

Samacheer Kalvi 12th Physics Semiconductor Electronics Short Answer Questions

Question 1.
Define electron motion in a semiconductor?
Answer:
To move the hole in a given direction, the valence electrons move in the opposite direction. Electron flow in an N – type semiconductor is similar to electrons moving in a metallic wire. The N – type dopant atoms will yield electron available for conduction.

Question 2.
Distinguish between intrinsic and extrinsic semiconductors.
Answer:
1. Intrinsic:

These are pure semiconducting tetravalent crystals.
Their electrical conductivity is low.
There is no permitted energy state between valence and conduction band.
Their electrical conductivity depends on temperature.

2. Extrinsic:

These are semiconducting tetravalent crystals doped with impurity atoms group III (or) V.
Their electrical conductivity is high.
There is no permitted energy state of the impurity atom between valence and conduction band.
Their electrical conductivity depends on temperature as well as dopant concentration.

Question 3.
What do you mean by doping?
Answer:
The process of adding impurities to the intrinsic semiconductor is called doping.

Question 4.
How electron-hole pairs are created in a semiconductor material?
Answer:
The free electrons from electron hole pairs, enable current to flow in the semiconductor when an external voltage is applied. The holes in the valence band also allow electron movement within the valence band itself and this also contributes to current flow. This process is called electron – hole pair generation.

Question 5.
A diode is called as a unidirectional device. Explain?
Answer:
Diode is called as a unidirectional device, i.e., current flows in only one direction (anode to cathode internally) when a forward voltage is applied, the diode conducts and when reverse voltage is applied, there is no conduction. A mechanical analogy is a rat chat, which allows motion in one direction only.

Question 6.
What do you mean by leakage current in a diode?
Answer:
The leakage current in a diode is the current that the diode will leak when a reverse voltage is applied to it. Under the reverse bias, a very small current in μA, flows across the junction. This is due to the flow of the minority charge carriers called the leakage current or reverse saturation current.

Question 7.
Draw the output waveform of a full wave rectifier.
Answer :
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Question 8.
Distinguish between avalanche and zener breakdown.
Answer:
1. Avalanche Breakdown:

It occurs in junctions which are lightly and have wide depletion widths.
It occurs at higher reverse voltages when thermally generated electrons get enough kinetic energy to produce more electrons by collision.
At reverse voltage above 6 V breakdown is due to avalanche effect.
Electric field produced is weak in nature.
Charge carriers obtain energy from the applied potential.

2. Zener Breakdown:

It occurs in junctions which are heavily doped and have narrow depletion widths.
It occurs due to rupture of covalent bonds by strong electric fields set up in depletion region by the reverse voltage.
At reverse voltage below 6V breakdown is due to zener effect.
A strong electric field is produced
Zener current is independent of applied voltage.

Question 9.
Discuss the biasing polarities in an NPN and PNP transistors.
Answer:
In a PNP transistor, base and collector will be negative with respect to emitter indicated by the middle letter N whereas base and collector will be positive in an NPN transistor [indicated by the middle letter P]

Question 10.
Explain the current flow in a NPN transistor?
Answer:

The conventional flow of current is based on the direction of the motion of holes
In NPN transistor, current enters from the base into the emitter.

Question 11.
What is the phase relationship between the AC input and output voltages in a common emitter amplifier? What is the reason for the phase reversal?
Answer:
In a common emitter amplifier, the input and output voltages are 180° out of phase or in, opposite phases. The reason for this can be seen from the fact that as the input voltage rises, so the current increases through the base circuit.

Question 12.
Explain the need for a feedback circuit in a transistor oscillator.
Answer:
The circuit used to feedback a portion of the output to the input is called the feedback network. If the portion of the output fed to the input is in phase with the input, then the magnitude of the input signal increases. It is necessary for sustained oscillations.

Question 13.
Give circuit symbol, logical operation, truth table, and Boolean expression of-

AND
OR
NOT
NAND
NOR
EX – OR gates.

Answer:
1. AND gate Circuit symbol:
A and B are inputs and Y is the output.
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It is a logic gate and hence A, B, and Y can have the (a) Two input AND gate value of either 1 or 0.

Boolean equation:
Y = A.B
It performs logical multiplication and is
different from arithmetic multiplication.
Logic operation:
The output of AND gate is high (1) only when all the inputs are high (1). The rest of the cases the output is low. Hence the output of AND gate is high (1) only when all the inputs are high.

2. OR gate:
Circuit Symbol
A and B are inputs and Y is the output.
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Boolean equation:
A + B = Y
It performs logical addition and is different from arithmetic addition.

Logic operation:
The output of OR gate is high (logic 1 state) when either of the inputs or both are high.

3. NOT gate:
Circuit symbol
A is the input and Y is the output.
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Boolean equation:
Y = $\overline { A } $

Logic operation:
The output is the complement of the input.
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It is represented with an overbar. It is also called as inverter. The truth table infers that the output Y is 1 when input A is 0 and vice versa. The truth table of NOT.

4. NAND gate:
A and B are inputs and Y is the output.
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Boolean equation:
Y = Y= $\overline { AB } $
Logic operation:
The output Y equals the complement of AND operation. The circuit is an AND gate followed by a NOT gate. Therefore, it is summarized as NAND. The output is at logic zero only when all the inputs are high. The rest of the cases, the output is high (Logic 1 state).

5. NOR gate:
Circuit symbol: A and B are inputs and Y is the output.
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Boolean equation:
Y= A + B
Logic operation:
Y equals the complement of OR operation (A OR B). The circuit is an OR gate followed by a NOT gate and is summarized as NOR. The output is high when all the inputs are low. The output is low for all other combinations of inputs.

6. Ex – OR gate:
Circuit symbol
A and B are inputs and Y is the output. The Ex-OR operation is denoted as ⊕.
Boolean equation:
Y = A. $\overline { B } $ + $\overline { A } $ .B
Y = A ⊕ B
Logic operation:
The output is high only when either of the two inputs is high. In the case of an Ex-OR gate with more than two inputs, the output will be high when odd number of inputs are high.
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Question 14.
State De Morgan’s first and second theorems De Morgan’s First Theorem?
Answer:
The first theorem states that the complement of the sum of two logical inputs is equal to the product of its complements.
$\overline { A+B } $ = $\overline { A } $.$\overline { B } $
De Morgan’s Second Theorem:
The second theorem states that the complement of the product of two inputs is equal to the sum of its complements.
$\overline { A.B } $ = $\overline { A+B } $

Samacheer Kalvi 12th Physics Semiconductor Electronics Long Answer Questions

Question 1.
Elucidate the formation of a N – type and P – type semiconductors.
Answer:
1. N – type semiconductor:
A n-type semiconductor is obtained by doping a pure Germanium (or Silicon) crystal with a dopant from group V pentavalent elements like Phosphorus, Arsenic, and Antimony. The dopant has five valence electrons while the Germanium atom has four valence electrons.

During the process of doping, a few of the Germanium atoms are replaced by the group V dopants. Four of the five valence electrons of the impurity atom are bound with the 4 valence electrons of the neighbouring replaced Germanium atom. The fifth valence electron of the impurity atom will be loosely attached with the nucleus as it has not formed the covalent bond.
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The energy level of the loosely attached fifth electron from the dopant is found just below the conduction band edge and is called the donor energy level. At room temperature, these electrons can easily move to the conduction band with the absorption of thermal energy. It is shown in the figure (c). Besides, an external electric field also can set free the loosely bound electrons and lead to conduction.

It is important to note that the energy required for an electron to jump from the valence band to the conduction band (E_g) in an intrinsic semiconductor is 0.7 eV for Ge and 1.1 eV for Si, while the energy required to set free a donor electron is only 0.01 eV for Ge and 0.05 eV for Si.

The group V pentavalent impurity atoms donate electrons to the conduction band and are called donor impurities. Therefore, each impurity atom provides one extra electron to the conduction band in addition to the thermally generated electrons. These thermally generated electrons leave holes in valence band. Hence, the majority carriers of current in an n-type Semiconductor are electrons and the minority carriers are holes. Such a semiconductor doped with a pentavalent impurity is called an n-type semiconductor.
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2. P – type semiconductor:
Here, a trivalent atom from group III elements such as Boron, Aluminium, Gallium and Indium is added to the Germanium or Silicon substrate. The dopant with three valence electrons are bound with the neighbouring Germanium atom as shown in Figure (a). As Germanium atom has four valence electrons, one electron position of the dopant in the Germanium crystal lattice will remain vacant. The missing electron position in the covalent bond is denoted as a hole.
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To make complete covalent bonding with all four neighbouring atoms, the dopant is in need of one more electron. These dopants can accept electrons from the neighbouring atoms. Therefore, this impurity is called an acceptor impurity. The energy level of the hole created by each impurity atom is just above the valence band and is called the acceptor-energy level, as shown in Figure (b).
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For each acceptor atom, there will be a hole in the valence band in addition to the thermally generated holes. In such an extrinsic semiconductor, holes are the majority carriers and thermally generated electrons are minority carriers. The semiconductor thus formed is called a p – type semiconductor.

Question 2.
Explain the formation of PN junction diode. Discuss its V-I characteristics.
Answer:
Formation of depletion layer:
A p – n junction is formed by joining n-type and p-type semiconductor materials as shown in figure.

(a) Since the n-region has a high electron concentration and the p-region a high hole concentration, electrons diffuse from the n-side to the p-side. This causes diffusion current which exists due to the concentration difference of electrons. The electrons diffusing into the p-region may occupy holes in that region and make it negative.

The holes left behind by these electrons in the n-side are equivalent to the diffusion of holes from the p-side to the n-side. If the electrons and holes were not charged, this diffusion process would continue until the concentration of electrons and holes on the two sides were the same, as happens if two gasses come into contact with each other.
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But, in a p – n junction, when the electrons and holes move to the other side of the junction, they leave behind exposed charges on dopant atom sites, which are fixed in the crystal lattice and are unable to move. On the n-side, positive ion cores are exposed and on the p-side, negative ion cores are exposed as shown in Figure

(b) An electric field E forms between the positive ion cores in the n – type material and negative ion cores in the p-type material. The electric field sweeps free carriers out of this region and hence it is called depletion region as it is depleted of free carriers. A barrier potential V_b due to the electric field E is formed at the junction as shown in Figure.

(c) As this diffusion of charge carriers from both sides continues, the negative ions form a layer of negative space charge region along the p-side. Similarly, a positive space charge region is formed by positive ions on the n-side. The positive space charge region attracts electrons from p-side to n-side and the negative space charge region attracts holes from n-side to p-side.

This moment of earners happen in this region due to the formed electric field and it constitutes a current called drift current. The diffusion current and drift current flow in the opposite direction and at one instant they both become equal. Thus, a p – n junction is formed.

V-I characteristics of a junction diode:
Forward characteristics:
It is the study of the variation in current through the diode with respect to the applied voltage across the diode when it is forward biased. An external resistance (R) is used to limit the flow of current through the diode. The voltage across the diode is varied by varying the biasing voltage across the dc power supply.

The forward bias voltage and the corresponding forward bias current are noted. A graph is plotted by taking the forward bias voltage (V) along the X – axis and the current (I) through the diode along the Y – axis. This graph is called the forward V-I characteristics of the p – n junction diode. Three inferences can be brought out from the graph:
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(i) At room temperature, a potential difference equal to the barrier potential is required before a reasonable forward current starts flowing across the diode. This voltage is known as threshold voltage or cut-in voltage or knee voltage (V_th). It is approximately 0.3 V for Germanium and 0.7 V for Silicon. The current flow is negligible when the applied voltage is less than the threshold voltage. Beyond the threshold voltage, increase in current is significant even for a small increase in voltage.

(ii) The graph clearly infers that the current flow is not linear and is exponential. Hence it does not obey Ohm’s law.

(iii) The forward resistance (r_f) of the diode is the ratio of the small change in voltage (∆V)to the small change in current(∆I), r_f = $\frac { ∆V }{ ∆I }$
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However, if the applied voltage is increased beyond a rated value, it will produce an extremely large current which may destroy the junction due to overheating. This is called as the breakdown of the diode and the voltage at which the diode breaks down is called the breakdown voltage. Thus, it is safe to operate a diode well within the threshold voltage and the breakdown voltage.

Reverse characteristics:
In the reverse bias, the p-region of the diode is connected to the negative terminal and n-region to the positive terminal of the dc power supply. A graph is drawn between the reverse bias voltage and the current across the junction, which is called the reverse characteristics of a p-n junction diode.

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Under this bias, a very small current in μA, flows across the junction. This is due to the flow of the minority charge carriers called the leakage current or reverse saturation current. Besides, the current is almost independent of the voltage. The reverse bias voltage can be increased only up to the rated value otherwise the diode will enter into the breakdown region.

Question 3.
Draw the circuit diagram of a half wave rectifier and explain its working Half wave rectifier circuit:
Answer:
The half wave rectifier circuit. The circuit consists of a transformer, a p-n junction diode and a resistor. In a half wave rectifier circuit, either a positive half or the negative half of the AC input is passed through while the other half is blocked. Only one half of the input wave reaches the output. Therefore, it is called half wave rectifier. Here, a p-n junction diode acts as a rectifying diode.
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During the positive half cycle:
When the positive half cycle of the ac input signal passes through the circuit, terminal A becomes positive with respect to terminal B. The diode is forward biased and hence it conducts. The current flows through the load resistor R_L and the AC voltage developed across R_L constitutes the output voltage V₀ and the waveform of the diode current.

During the negative half cycle:
When the negative half cycle of the ac input signal passes through the circuit, terminal A is negative with respect to terminal B. Now the diode is reverse biased and does not conduct and hence no current passes through R_L. The reverse saturation current in a diode is negligible. Since there is no voltage drop across R_L, the negative half cycle of ac supply is suppressed at the output.

The output of the half wave rectifier is not a steady dc voltage but a pulsating wave. This pulsating voltage is not sufficient for electronic equipments. A constant or a steady voltage is required which can be obtained with the help of filter circuits and voltage regulator circuits. Efficiency (η) is the ratio of the output dc power to the ac input power supplied to the circuit. Its value for half wave rectifier is 40.6 %.

Question 4.
Explain the construction and working of a full w ave rectifier.
Answer:
Full wave rectifier:
The positive and negative half cycles of the AC input signal pass through the full wave rectifier circuit and hence it is called the full wave rectifier. It consists of two p-n junction diodes, a center tapped transformer, and a load resistor (R_L). The centre is usually taken as the ground or zero voltage reference point. Due to the centre tap transformer, the output voltage rectified by each diode is only one half of the total secondary voltage.
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During positive half cycle:
When the positive half cycle of the ac input signal passes through the circuit, terminal M is positive, G is at zero potential and N is at negative potential. This forward biases diode D₁ and reverse biases diode D₂. Hence, being forward biased, diode D₁ conducts and current flows along the path MD₁ AGC. As a resul t, positive half cycle of the voltage appears across R_L in the direction G to C.

During negative half cycle:
When the negative half cycle of the ac input signal passes through the circuit, terminal N is positive, G is at zero potential and M is at negative potential. This forward biases diode D₂ and reverse biases diode D₁. Hence, being forward biased, diode D₂ conducts and current flows along the path ND₂ BGC . As a result, negative half cycle of the voltage appears across R_L in the same direction from G to C.

Hence in a full wave rectifier both positive and negative half cycles of the input signal pass through the circuit in the same direction as shown in figure (b). Though both positive and negative half cycles of ac input are rectified, the output is still pulsating in nature. The efficiency (η) of full wave rectifier is twice that of a half wave rectifier and is found to be 81.2 %. It is because both the positive and negative half cycles of the ac input source are rectified.

Question 5.
What is an LED? Give the principle of operation with a diagram.
Answer:
Light Emitting Diode (LED):
LED is a p – n junction diode which emits visible or invisible light when it is forward biased. Since, electrical energy is converted into light energy, this process is also called electroluminescence. The cross-sectional view of a commercial LED is shown in figure (b). it consists of a p-layer, n-layer and a substrate. A transparent window is used to allow light to travel in the desired direction. An external resistance in series with the biasing source is required to limit the forward current through the LED. In addition, it has two leads; anode and cathode:
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When the p – n junction is forward biased, the conduction band electrons on n-side and valence band holes on p-side diffuse across the junction. When they cross the junction, they become excess minority carriers (electrons in p-side and holes in n-side).

These excess minority carriers recombine with oppositely charged majority carriers in the respective regions, i.e. the electrons in the conduction band recombine with holes in the valence band as shown in the figure (c). During recombination process, energy is released in the form of light (radiative) or heat (non-radiative). For radiative recombination, a photon of energy hυ is emitted.

For non-radiative recombination, energy is liberated in the form of heat. The colour of the light is determined by the energy band gap of the material. Therefore, LEDs are available in a wide range of colours such as blue (SiC), green (AlGaP) and red (GaAsP). Now a days, LED which emits white light (GalnN) is also available.

Question 6.
Write notes on Photodiode?
Answer:
Photodiodes:
A p-n junction diode which converts an optical signal into electric current is known as photodiode. Thus, the operation of photodiode is exactly opposite to that of an LED. Photo diode words in reverse bias. Its circuit symbol is shown in figure (a). The direction of arrows indicates that the light is incident on the photo diode.

The device consists of a p – n junction semiconductor made of photosensitive material kept safely inside a plastic case. It has a small transparent window that allows light to be incident on the p – n junction. Photodiodes can generate current when the p – n junction is exposed to light and hence are called as light sensors.
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When a photon of sufficient energy (hυ) strikes the depletion region of the diode, some of the valence band electrons are elevated into conduction band, in turn holes are developed in the valence band. This creates electron – hole pairs. The amount of electron – hole pairs generated depends on the intensity of light incident on the p-n junction. These electrons and holes are swept across the p-n junction by the electric field created by reverse voltage before recombination takes place. Thus, holes move towards the n-side and electrons towards the p-side.

When the external circuit is made, the electrons flow through the external circuit and constitute the photocurrent. When the incident light is zero, there exists a reverse current which is negligible. This reverse current in the absence of any incident light is called dark current and is due to the thermally generated minority carriers.

Question 7.
Explain the working principle of a solar cell. Mention its applications.
Answer:
Solar cell:
A solar cell, also known as photovoltaic cell, converts light energy directly into electricity or electric potential difference by photovoltaic effect. It is basically a p – n junction which generates emf when solar radiation falls on the p – n junction. A solar cell is of two types: p-type and n-type. Both types use a combination of p-type and n-type Silicon which together forms the p-n junction of the solar cell.

The difference is that p-type solar cells use p-type Silicon as the base with an ultra-thin layer of n-type Silicon as shown in Figure, while n-type solar cell uses the opposite combination. The other side of the p-Silicon is coated with metal which forms the back electrical contact. On top of the n-type Silicon, metal grid is deposited which acts as the front electrical contact. The top of the solar cell is coated with anti-reflection coating and toughened glass.
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In a solar cell, electron-hole pairs are generated due to the absorption of light near the junction. Then the charge carriers are separated due to the electric field of the depletion region. Electrons move towards n-type Silicon and holes move towards p-type Silicon layer. The electrons reaching the n-side are collected by the front contact and holes reaching p-side are collected by the back electrical contact.

Thus a potential difference is developed across solar cell. When an external load is connected to the solar cell, photocurrent flows through the load. Many solar cells are connected together either in series or in parallel combination to form solar panel or module. Many solar panels are connected with each other to form solar arrays. For high power applications, solar panels and solar arrays are used.
Applications:

Solar cells are widely used in calculators, watches, toys, portable power supplies, etc.
Solar cells are used in satellites and space applications
Solar panels are used to generate electricity.

Question 8.
Sketch the static characteristics of a common emitter transistor and bring out the essence of input and output characteristics.
Answer:
Static Characteristics of Transistor in Common Emitter Mode:
The know-how of certain parameters like the input resistance, output resistance, and current gain of a transistor are very important for the effective use of transistors in circuits. The circuit to study the static characteristics of an NPN transistor in the common emitter mode is given in figure.

The bias supply voltages V_BB and V_CC bias the base-emitter junction and collector- emitter junction respectively. The junction potential at the base-emitter is represented as V_BE and the collector-emitter as V_CE. The rheostats R₁ and R₂, are used to vary the base and collector currents respectively.
The static characteristics of the BJT are:

Input characteristics
Output characteristics
Transfer characteristics

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1. Input Characteristics:
Input Characteristics curves give the relationship between the base current (I_B) and base to emitter voltage (V_BE) at constant collector to emitter voltage (V_CE) and are shown in figure. Initially, the collector to emitter voltage (V_CE) is set to a particular voltage (above 0.7 V to reverse bias the junction). Then the base-emitter voltage (V_BE) is increased in suitable steps and the corresponding base-current (I_B) is recorded. A graph is plotted with V_BE along the x-axis and I_B along the y-axis. The procedure is repeated for different values of V_CE.
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The following observations are made from the graph:

1. The curve looks like the forward characteristics of an ordinary p-n junction diode.

2. There exists a threshold voltage or knee voltage (V_k) below which the base current is very small. The value is 0.7 V for Silicon and 0.3 V for Germanium transistors. Beyond the knee voltage, the base current increases with the increase in base-emitter voltage.

3. It is also noted that the increase in the collector-emitter voltage decreases the base current. This shifts the curve outward. This is because the increase in collector-emitter voltage increases the width of the depletion region in turn, reduces the effective base width and thereby the base current.

Input resistance:
The ratio of the change in base-emitter voltage (∆V_BE) to the change in base current (∆I_B) at a constant collector-emitter voltage (V_CE) is called the input resistance (R_i). The input resistance is not linear in the lower region of the curve.
R_i =$\left(\frac{\Delta \mathrm{V}_{\mathrm{BE}}}{\Delta \mathrm{I}_{\mathrm{B}}}\right)_{\mathrm{V}_{\mathrm{CB}}}$

The input resistance is high for a transistor in common emitter configuration. Output Characteristics:
The output characteristics give the relationship between the variation in the collector current (∆I_C) with respect to the variation in collector- emitter voltage (∆ V_CE) at constant input current (I_B) as shown in figure.
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Initially, the base current (I_B) is set to a particular value. Then collector- emitter voltage (V_CE) is increased in suitable steps and the corresponding collector current (I_C) is recorded. A graph is plotted with the V_CE along the x-axis and I_C along the y-axis.

This procedure is repeated for different values of I_B, The four regions in are:
(i) Saturation region:
When V_CE is increased above 0 V, the Ic increases rapidly to a saturation value almost independent of I_B (Ohmic region, OA) called knee voltage. Transistors are always operated above this knee voltage.

(ii) Cut-off region:
A small collector current (I_C) exists even after the base current (I_B) is reduced to zero. This current is due to the presence of minority carriers across the collector-base junction and the surface leakage current (I_CEO). This region is called as the cut-off region, because the main collector current is cut-off.

(iii) Active region:
In this region, the emitter-base junction is forward biased and the collector-base junction is reverse biased. The transistor in this region can be used for voltage, current and power amplification.

(iv) Breakdown region:
If the collector-emitter voltage (V_CE) is increased beyond the rated value given by the manufacturer, the collector current (I_C) increases enormously leading to the junction breakdown of the transistor. This avalanche breakdown can damage the transistor.

Output Resistance:
The ratio of the change in the collector-emitter voltage (∆V_CE) to the corresponding change in the collector current (∆I_C) at constant base current (I_B ) is called output resistance (R_O).
R₀ =$\left(\frac{\Delta \mathrm{V}_{\mathrm{CE}}}{\Delta \mathrm{I}_{\mathrm{C}}}\right)_{\mathrm{I}_{\mathrm{B}}}$
The output resistance for transistor in common emitter configuration is very low.

Question 9.
Describe the function of a transistor as an amplifier with the neat circuit diagram. Sketch the input and output wave form.
Answer:
Transistor as an amplifier:
A transistor operating in the active region has the capability to amplify weak signals. Amplification is the process of increasing the signal strength (increase in the amplitude). If a large amplification is required, the transistors are cascaded with coupling elements like resistors, capacitors, and transformers which is called as multistage amplifiers.

Here, the amplification of an electrical signal is explained with a single stage transistor amplifier as shown in figure (a). Single stage indicates that the circuit consists of one transistor with the allied components. An NPN transistor is connected in the common emitter Configuration.
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To start with, the Q point or the operating point of the transistor is fixed so as to get the maximum signal swing at the output (neither towards saturation point nor towards cut-off). A load resistance, R_C is connected in series with the collector circuit to measure the output voltage. The capacitor C₁ allows only the ac signal to pass through. The emitter bypass capacitor C_E provides a low reactance path to the amplified ac signal. The coupling capacitor C_C is used to couple one stage of the amplifier with the next stage while constructing multistage amplifiers. V_S is the sinusoidal input signal source applied across the base-emitter.
Collector currrent ,I_c = Iβ_B = [∴β=$\frac { { I }_{ C } }{ { I }_{ B } } $]
Applying Kirchhoff’s voltage law in the output loop, the collector-emitter voltage is given by
V_CE = V_CC – I_CR_C

Working of the amplifier:
1. During the positive half cycle:
Input signal (V_S) increases the forward voltage across the emitter-base. As a result, the base current (I_B) increases. Consequently, the collector current (I_C) increases β times. This increases the voltage drop across R_C which in turn decreases the collector-emitter voltage (V_CE). Therefore, the input signal in the positive direction produces an amplified signal in the negative direction at the output. Hence, the output signal is reversed by 180° as shown in figure (b).

2. During the negative half cycle:
Input signal (V_s ) decreases the forward voltage across the emitter-base. As a result, base current (I_B) decreases and in turn increases the collector current (I_C). The increase in collector current (I_C) decreases the potential drop across Rc and increases the collector-emitter voltage (V_CE). Thus, the input signal in the negative direction produces an amplified signal in the positive direction at the output. Therefore, 180° phase reversal is observed during the negative half cycle of the input signal.

Question 10.
Transistor functions as a switch. Explain.
Answer:
The transistor in saturation and cut – off regions functions like an electronic switch that helps to turn ON or OFF a given circuit by a small control signal.
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1. Presence of dc source at the input (saturation region):
When a high input voltage (V_in = +5V) is applied, the base current (I_B) increases and in turn increases the collector current. The transistor will move into the saturation region (turned ON). The increase in collector current (I_C) increases the voltage drop across Rc, thereby lowering the output voltage, close to zero. The transistor acts like a closed switch and is equivalent to ON condition.

2. Absence of dc source at the input (cut-off region):
A low input voltage (V_in = 0V), decreases the base current (I_B) and in turn decreases the collector current (I_c). The transistor will move into the cut-off region (turned OFF). The decrease in collector current (Ic) decreases the drop across Rc, thereby increasing the output voltage, close to +5 V.

The transistor acts as an open switch which is considered as the OFF condition. It is manifested that, a high input gives a low output and a low input gives a high output. In addition, we can say that the output voltage is opposite to the applied input voltage. Therefore, a transistor can be used as an inverter in computer logic circuitry.

Question 11.
State Boolean laws. Elucidate how they are used to simplify Boolean expressions with suitable example.
Answer:
Law’s of Boolean Algebra: The NOT, OR and AND operations are $\overline { A } $, A + B, A . B are the Boolean operations. The results of these operations can be summarised as:
Complement law
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-34
The complement law can be realised as
OR laws:

AND laws:
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-36
The Boolean operations obey the following laws.
Commutative laws
A+ B = B + A
A. B = B . A
Associative laws
A + (B + C) = (A + B) + C
A . (B . C) = (A .B) . C
Distributive laws
A( B + C) = AB + AC
A + BC = (A + B) (A + C)
The above laws are used to simplify complicated expressions and to simplify the logic circuitry.

Question 12.
State and prove De Morgan’s First and Second theorems.
Answer:
De Morgan’s First Theorem:
The first theorem states that the complement of the sum of two logical inputs is equal to the product of its complements.
Proof:
The Boolean equation for NOR gate is Y = $\overline { A+B } $. The Boolean equation for a bubbled AND gate is Y = $\overline { A } $. $\overline { B } $ . Both cases generate same outputs for same inputs. It can be verified using the following truth table.
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-37
From the above truth table, we can conclude $\overline { A+B } $ = $\overline { A } $. $\overline { B } $ . Thus De Morgan’s First Theorem is proved. It also says that a NOR gate is equal to a bubbled AND gate. The corresponding logic circuit diagram is shown in figure.
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-38

De Morgan’s Second Theorem:
The second theorem states that the complement of the product of two inputs is equal to the sum of its complements.
Proof:
The Boolean equation for NAND gate is Y = $\overline { AB } $
The Boolean equation for bubbled OR gate is Y = $\overline { A } $ + $\overline { B } $ . A and B are the inputs and Y is the output. The above two equations produces the same output for the same inputs. It can be verified by using the truth table.
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-39
From the above truth table we can conclude $\overline { A.B } $ = $\overline { A } $ + $\overline { B } $. Thus De Morgan’s Second Theorem is proved. It also says, a NAND gate is equal to a bubbled OR gate. The corresponding logic circuit diagram is shown in figure.
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-40

Samacheer Kalvi 12th Physics Semiconductor Electronics Numerical Problems

Question 1.
The given circuit has two ideal diodes connected as shown in figure below. Calculate the current flowing through the resistance R₁.
Answer:
Diode D₁ is reverse biased so, it will block the current and Diode D₂ is forward biased, so it will pass the current.
Current in the circuit is
I = $\frac { V }{ { R }_{ s } } $ = $\frac { 10 }{ 2+2 }$ = $\frac { 10 }{ 4 }$ = 2.5 a
I = 2.5 A

Question 2.
Four silicon diodes and a 10 resistor are connected as shown in figure below. Each diode has a resistance of 1Ω Find the current flows through the 18Ω resistor.
Answer:
Diodes D₂ and D₄ are forward biased while diodes D₁ and D₃ are reverse biased. Only current flowing through the closed loop is EADCBFE. Consider the applied voltage is 4V. For silicon diode, Barrier Voltage is 0.7V.
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-41
Net circuit Voltages = 4 – (0.7 + 0.7) = 4 1.4
V = 2.6 V
Total circuit resistance = 1 + 18 + 1
R = 20 Ω
∴ Circuit Current I = $\frac { V }{ R }$ = $\frac { 2.6 }{ 20 }$

Question 3.
Assuming V_CEsat = 0.2 V and β = 50, find the minimum base current (I_B) required to drive the transistor given in the figure to saturation.
Solution:
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics q3

Question 4.
A transistor having α =0.99 and V_BE = 0.7V, is given in the circuit. Find the value of the collector current.
Solution:
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-43

Question 5.
In the circuit shown in the figure, the BJT has a current gain (β) of 50. For an emitter – base voltage V_EB = 600 mV, calculate the emitter – collector voltage V_EC (in volts).
Solution:
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics q3

Samacheer Kalvi 12th Physics Semiconductor Electronics Additional Questions

Samacheer Kalvi 12th Physics Semiconductor Electronics Multiple Choice Questions

Question 1.
The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature
(a) increase exponentially with increasing band gap
(b) decrease exponentially with increasing band gap
(c) decreases with increasing temperature
(d) is independent of the temperature and the band gap.
Answer:
(b) decrease exponentially with increasing band gap
Hint:
At a finite temperature, the probability of jumping an electron from valence band to conduction band decreases exponentially with the increasing band gap (E_g )
n = n₀ e^-E_g/k_BT

Question 2.
The electrical conductivity of a semiconductor increase when electromagnetic radiation of wavelength shorter than 2480 nm is incident on it. The band gap (in eV) for the semiconductor is-
(a) 0.9
(b) 0.7
(c) 0.5
(d) 1.1.
Answer:
(c) 0.5
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-46

Question 3.
Which of the following statements is not true?
(a) The resistance of intrinsic semiconductor decreases with increase of temperature.
(b) Doping pure Si with trivalent impurities gives p-type semiconductors.
(c) The majority carriers in n-type semiconductors and holes
(d) Ap-n junction can act as a semiconductor diode.
Answer:
(c) The majority carriers in n-type semiconductors and holes
Hint:
The majority charge carriers in n-type semiconductors are electrons not holes. Only option (c) is not true.

Question 4.
Holes are charge carrier in
(a) intrinsic semiconductors
(b) ionic solids
(c) p-type semiconductor
(d) metals.
Answer:
(a) intrinsic semiconductors
Hint:
(a) In intrinsic semiconductor, n_h = n_e
(b) In P-type semiconductor, n_h >> n_e

Question 5.
A transistor is used in the common emitter mode as an amplifier. Then
(a) the base – emitter junction is forward – biased
(b) the base – emitter junction is reverse – biased
(c) the input signal is connected in series with the voltage applied to bias the base – emitter junction
(d) the input signal is connected in series with the voltage applied to bias the base – collector junction.
Answer:
(c) the input signal is connected in series with the voltage applied to bias the base – emitter junction
Hint:
In CE – transistor amplifier, the base – emitter junction is forward bias and the input signal is connected in series with the base – emitter battery.

Question 6.
The energy band gap is maximum in-
(a) metals
(b) superconductors
(c) insulators
(d) semiconductors.
Answer:
(c) insulators
Hint:
The band gap is maximum in insulators.

Question 7.
At absolute zero, Si acts as-
(a) non – metal
(b) metal
(c) insulator
(d) none of these.
Answer:
(c) insulator
Hint:
At absolute zero, Si acts as an insulator due to the absence of free electrons in the conduction band.

Question 8.
Apiece of copper and another of germanium are cooled from room temperature to 77 K. The resistance of
(a) each of these decreases
(b) copper strip increases and that of germanium decreases
(c) copper strip decreases and that of germanium increases
(d) each of these increases.
Answer:
(c) copper strip decreases and that of germanium increases
Hint:
With the decrease of temperature, the resistance of copper (a metallic conductor) decreased while that of germanium (a semiconductor) increases.

Question 9.
In the middle of the depletion layer of reverse biased p – n junction, the-
(a) electric field is zero
(b) potential is zero
(c) potential is maximum
(d) electric field is maximum.
Answer:
(a) electric field is zero
Hint:
When a p – n junction is reverse biased, the width of the depletion layer becomes large and so the electric field (E = v/d) becomes very small, nearly zero.

Question 10.
In a full wave rectifier circuit operating from 50 Hz mains, frequency, the fundamental frequency in the ripple would be-
(a) 50 Hz
(b) 25 Hz
(c) 100 Hz
(d) 70.7 Hz.
Answer:
(c) 100 Hz
Hint:
The frequency of the ripple in the output of a fullwave rectifier is twice the frequency of the a.c. input. Hence, it is 100 Hz.

Question 11.
The part of a transistor, which is heavily doped to produce a large number of majority carriers is called?
(a) emitter
(b) base
(c) collector
(d) any one out of emitter, base and collector.
Answer:
(a) emitter
Hint:
Emitter of a transistor is heavily doped so as to act as source of majority charge carriers.

Question 12.
When n – p – n transistor is used as an amplifier, then-
(a) electrons move from base to collector
(b) holes move from emitter to base
(c) electrons move from collector to base
(d) holes move from base to emitter.
Answer:
(a) electrons move from base to collector
Hint:
When n – p – n transistor is in operation, the majority charge carriers, i.e., electrons move from emitter to base and then to collector.

Question 13.
In a common – base amplifier, the phase difference between the input signal voltage and the output voltage (across collector and base) is
(a) 0
(b) π/4
(c) π/2
(d) π.
Answer:
(a) 0
Hint:
In a common – base amplifier, the input and output voltages are in the same phase.

Question 14.
In a common – base mode of a transistor, the collector current is 5.488 mA for an emitter current of 5.60 A. The value of the base current amplification factor (β) will be-
(a) 49
(b) 50
(c) 51
(d) 48.
Answer:
(a) 49
Hint:
β = $\frac { { I }_{ C } }{ { I }_{ B } } $ = $\frac { 5.488 }{ 0.112 }$ = 49.

Question 15.
In the circuit below, A and B represent two inputs and C represents the output. The circuit represents
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-47
(a) OR gate
(b) NOR gate
(c) AND gate
(d) NAND gate.
Answer:
(a) OR gate
Hint:
The given circuit represents an OR gate, when either A or B or both inputs are high, the output C is high.

Question 16.
In a fee lattice structure, what is the effective number of atoms?
(a) 4
(b) 3
(c) 2
(d) 1.
Answer:
(a) 4
Hint:
N = $\frac { { N }_{ C } }{ 8 } $ + $\frac { { N }_{ F } }{ 2 } $ = $\frac { 8 }{ 8 }$ + $\frac { 6 }{ 2 }$ = 4.

Question 17.
Monoclinic crystal lattice has dimensions-
(a) α = β = γ
(b) α = β = 90°, γ ≠ 90°
(e) α ≠ β ≠ γ
(d) none of these.
Answer:
(b) α = β = 90°, γ ≠ 90°
Hint:
For a monoclinic crystal, α ≠ β ≠ c and α = β = 90°≠ γ.

Question 18.
In insulators?
(a) valence band is partially filled
(b) conduction band is partially filled with electrons
(c) conduction band is filled with electrons and valence band is empty
(d) conduction band is empty and valence band is completely filled with electrons.
Answer:
(d) conduction band is empty and valence band is completely filled with electrons.
Hint:
In insulators, the conduction band is empty and valence band is completely filled with electrons.

Question 19.
The valence band and conduction band of a solid overlap at low temperature, the solid may be-
(a) a metal
(b) a semiconductor
(c) an insulator
(d) none of these.
Answer:
(a) a metal
Hint:
In metals, the valence band and conduction band may overlap at low temperature.

Question 20.
If germanium is dopped with arsenic, that will result in-
(a) n-type semiconductor
(b) p-type semiconductor
(c) intrinsic semiconductor
(d) none of these.
Answer:
(a) n-type semiconductor
Hint:
Arsenic is pentavalent. Its doping with germanium results in n-type semiconductor.

Question 21.
n-type semiconductor is
(a) positive charged
(b) negatively charged
(c) neutral
(d) positive or negative depending upon doping material.
Answer:
(c) neutral
Hint:
Semiconductors maintain their electrical neutrality even after doping.

Question 22.
To a germanium ciystal equal number of aluminium and indium atoms are added. Then
(a) it remains an intrinsic semiconductor
(b) it becomes an n-type semiconductor
(c) it becomes a p-type semiconductor
(d) it becomes an insulator.
Answer:
(c) it becomes a p-type semiconductor
Hint:
Both A1 and In are trivalent atoms. Their doping in germanium results in a p-type semiconductor.

Question 23.
The dominant contribution to current comes from holes in case of-
(a) metals
(b) intrinsic semiconductors
(c) p-type extrinsic semiconductors
(d) n-type extrinsic semiconductors.
Answer:
(c) p-type extrinsic semiconductors
Hint:
Holes are the majority charge carriers in p-type extrinsic semiconductors.

Question 24.
For a heavily doped n-type semiconductor, fermi – level lies-
(a) a little below the conduction band
(b) a little above the valence band
(c) a little inside the valence band
(d) at the centre of the band gap.
Answer:
(a) a little below the conduction band
Hint:
For a heavily doped n-type semiconductor, the fermi level lies slightly below the bottom of the conduction band.

Question 25.
The coordination number for a bcc crystal is-
(a) 4
(b) 8
(c) 12
(d) 6.
Answer:
(b) 8
Hint:
The eight comer atoms of the unit cell are close neighbourers of the atom at the body centre.

Question 26.
If the forward voltage in a diode is increased the width of the depletion region-
(a) increases
(b) decreases
(c) fluctuates
(d) no change.
Answer:
(b) decreases
Hint:
If the forward voltage in a diode is increased, the width of depletion region decreases.

Question 27.
In order to rectify an alternating current one uses a-
(a) thermocouple
(b) diode
(c) triode
(d) transistor.
Answer:
(b) diode
Hint:
A diode is used to rectify an alternating current.

Question 28.
Why is there sudden increase in current in zener diode?
(a) due to rupture of bonds
(b) resistance of depletion layer becomes less
(c) due to high doping
(d) none of the above.
Answer:
(a) due to rupture of bonds
Hint:
The sudden increase in current in a zener diode is due to the rupture of many covalent bonds.

Question 29.
In a transistor
(a) there is 1 p – n junction
(b) there are 2 p – n junction
(c) there are 3 p – n junction
(d) none of the above.
Answer:
(b) there are 2 p – n junction
Hint:
A transistor is like a combination of two p-n junctions placed back to back.

Question 30.
Let i_e, i_c and i_b represent emitter current, collector current and the base current of a transistor, then
(a) i_c > i_e
(b) i_b > i_c
(c) i_b < i_c
(d) i_e > i_c
Answer:
(d) i_e > i_c
Hint:
As i_e = i_c + i_b
∴ i_i >_c

Question 31.
In common – emitter amplifier the ratio $\frac { { I }_{ C } }{ { I }_{ E } } $ is 0.98. The current gain will be
(a) 4.9
(b) 7.8
(c) 49
(d) 78.
Answer:
(c) 49
Hint:
$\frac { α }{ 1-α } $ = $\frac { 0.98 }{ 1-0.98 } $ = $\frac { 0.98 }{ 0.02 } $ = 49

Question 32.
The gate for which output is high, if atleast one input is low?
(a) NAND
(b) NOR
(c) AND
(d) OR.
Answer:
(a) NAND
Hint:
The output of a NAND gate is high, if atleast one input is low.

Question 33.
An oscillator is nothing but an amplifier with-
(a) positive feedback
(b) large gain
(c) no feedback
(d) negative feedback.
Answer:
(a) positive feedback
Hint:
When a transistor is used as an amplifier with positive feedback, it works as an oscillator.

Question 34.
Crystalline solid are?
(a) anisotropic
(b) isotropic
(c) amporphus
(d) none of these.
Answer:
(a) anisotropic
Hint:
Crystalline solids are anisotropic as they show different physical properties along different directions.

Question 35.
Which of the following is an amorphous solid?
(a) Glass
(b) Diamond
(c) Salt
(d) Sugar.
Answer:
(a) Glass

Question 36.
Energy required to break one band in DNA is
(a) ≈ 1 eV
(b) ≈ 0.1 eV
(c) ≈ 0.01 eV
(d) ≈ 2.1 eV.
Answer:
(a) ≈ 1 eV
Hint:
The bond strength in DNA is nearly 1 eV.

Question 37.
An intrinsic semiconductor, at the absolute zero temperature, behaves like a/an?
(a) insulator
(b) superconductor
(c) n-type semiconductor
(d) p-type semiconductor.
Answer:
(a) insulator
Hint:
At the absolute zero temperature, an intrinsic semiconductor behaves like an insulator.

Question 38.
In a semiconducting material the mobilities of electrons and holes are µ_e and µ_h respectively. Which of the following is true?
(a) µ_e > µ_h
(b)µ_e < µ_h
(c) µ_e = µ_h
(d)µ_e < 0 ; µ_h > 0.
Answer:
(a) µ_e > µ_h
Hint:
The mobility of an electron in the conduction is more than the mobility of a hole in the valence band.

Question 39.
In a pure semiconductor crystal, if current flows due to breakage of crystal bonds, then the semiconductor is called
(a) acceptor
(b) donor
(c) intrinsic semiconductor
(d) extrinsic semiconductor.
Answer:
(c) intrinsic semiconductor
Hint:
Pure semiconductors are called intrinsic semiconductors.

Question 40.
Which of the following, when added as an impurity into the silicon, produces n-type semiconductor?
(a) phosphorous
(b) aluminium
(c) magnesium
(d) both (b) and (c).
Answer:
(a) phosphorous
Hint:
As phosphorous is pentavalent, it produces n-type semiconductor when added to silicon.

Question 41.
In n-type semiconductors, majority charge carriers are
(a) holes
(b) protons
(c) neutrons
(d) electrons.
Answer:
(d) electrons

Question 42.
In p-type semiconductor,
(a) major current carrier are electrons
(b) major carrier are mobile negative ions
(c) major carrier are mobile holes
(d) the number of mobile holes exceeds the number of acceptor atoms.
Answer:
(c) major carrier are mobile holes
Hint:
In p-type semiconductors, holes are the majority charge carriers.

Question 43.
The potential barrier in the depletion layer is due to-
(a) ions
(b) holes
(c) electrons
(d) forbidden band.
Answer:
(a) ions
Hint:
The potential barrier in the depletion layer is due to the presence of immobile ions.

Question 44.
When a p-n diode is reverse biased, then
(a) no current flows
(b) the depletion region is increased
(c) the depletion region is reduced
(d) the height of the potential barrier is reduced.
Answer:
(b) the depletion region is increased
Hint:
When a p-n junction is reverse biased, its depletion region is widened.

Question 45.
If a p-n diode is reverse biased, then the resistance measured by an ohm meter, will be
(a) zero
(b) low
(c) high
(d) infinite.
Answer:
(c) high
Hint:
When a p-n diode is reverse biased, it offers a high resistance.

Question 46.
Diode is used as an/a?
(a) oscillator
(b) amplifier
(c) rectifier
(d) modulator.
Answer:
(c) rectifier

Question 47.
In the half wave rectifier circuit operating from 50 Hz main frequency, the fundamental frequency in the ripple would be-
(a) 25 Hz
(b) 50 Hz
(c) 70.7 Hz
(d) 100 Hz
Answer:
(b) 50 Hz.
Hint:
In a half wave rectifier, fundamental frequency in the ripple = Input frequency = 50 Hz.

Question 48.
Zener diode acts as a/an?
(a) oscillator
(b) regulator
(c) rectifier
(d) filter.
Answer:
(b) regulator

Question 49.
A transistor is a/an?
(a) chip
(b) insulator
(c) semiconductor
(d) metal.
Answer:
(c) semiconductor

Question 50.
The minimum potential difference between the base and emitter required to switch a silicon transistor ON is approximately.
(a) IV
(b) 3V
(c) 5V
(d) 4.2 V.
Answer:
(a) IV
Hint:
For switching on a silicon transistor, (V_BE)_min ≈ 1V.

Question 51.
When n-p-n transistor is used as an amplifier, then
(a) holes moves from emitter
(b) electrons move from base to collector
(c) holes move from base to emitter
(d) electrons move from collector to base.
Answer:
(b) electrons move from base to collector

Question 52.
The current gain for a transistor working as common base amplifier is 0.96. If the emitter current is 7.2 mA, then the base current is-
(a) 0.29 mA
(b) 0.35 mA
(c) 0.39 mA
(d) 0.43 mA.
Answer:
(a) 0.29 mA
Hint:
α = $\frac { { I }_{ C } }{ { I }_{ E } } $ (or) 0.96 = $\frac { { I }_{ C } }{ 7.2mA} $
I_C = 0.96 x 7.2 = 6.91 mA
I_B = I_C – I_E = 7.2 – 6.91 =0.29 mA.

Question 53.
Consider an n-p-n transistor amplifier in common – emitter configuration. The current gain of the transistor is 100. If the collector current changes by 1 mA, what will be the change in emitter current?
(a) 1.1 mA
(b) 1.01 mA
(c) 0.01 mA
(d) 10 mA.
Answer:
(b) 1.01 mA
Hint:
β = $\frac { { \triangle I }_{ C } }{ { \triangle I }_{ E } } $ ∴ ∆I_B = $\frac { { \triangle I }_{ C } }{ β } $ = $\frac { 1mA }{ β }$ = 0.01 mA
∆I_E= ∆I_B + ∆I_C = 0.01 + 1 = 1.01 mA.

Question 54.
An amplifier has voltage gain = 1000. The voltage gain (in dB) is-
(a) 30 dB
(b) 60 dB
(c) 3 dB
(d) 20 dB.
Answer:
(b) 60 dB
Hint:
Voltage gain in dB = 20 log₁₀ A_v= 20 log₁₀ (1000) = 20 x 3 = 60 dB.

Question 55.
Boolean algebra is essentially based on-
(a) logic
(b) truth
(c) numbers
(d) symbol.
Answer:
(a) logic

Question 56.
The number (0) zero is required for-
(a) transistor
(b) abacus
(c) computer
(d) calculator.
Answer:
(c) computer
Hint:
A computer work on binary digits 0 and 1.

Question 57.
Which of the following logic gates in a universal gate?
(a) OR
(b) NOT
(c) AND
(d) NAND.
Answer:
(d) NAND.
Hint:
NAND gate is a universal gate because its repeated use can give all basic gates like OR, AND and NOT gates.

Question 58.
Which of the following is the weakest kind of the bonding in solids?
(a) Ionic
(b) Metallic
(c) Van der waals
(d) Covalent.
Answer:
(c) Van der waals

Question 59.
The cations and anions are arranged in alternate form in-
(a) metallic crystal
(b) ionic crystal semi – conductor
(c) covalent crystal
(d) crystal.
Answer:
(b) ionic crystal semi – conductor

Question 60.
Diamond is very hard because-
(a) it is covalent solid
(b) it has large cohesive energy
(c) high melting point
(d) insoluble in all solvents.
Answer:
(b) it has large cohesive energy

Question 61.
Number of atoms per unit cell in bcc lattice is-
(a) 9
(b) 4
(c) 2
(d) 1.
Answer:
(c) 2
Hint:
N = N_B + $\frac { { N }_{ C } }{ 8 } $ = 1 + $\frac { 8 }{ 8 }$ = 2.

Question 62.
At absolute zero, Si acts as?
(a) non metal
(b) metal
(c) 2
(d) 1.
Answer:
(c) 2
Hint:
At absolute zero, Si acts as an insulator because it has no free electrons in the conduction band.

Question 63.
Which of the following, when added as an impurity into the silicon produces n-type semi – conductor?
(a) B
(b) AL
(c) P
(d) Mg.
Answer:
(c) P
Hint:
Only P is a pentavalent impurity atom,its doping with germanium produces a p-types semi – conductor.

Question 64.
To obtain a p-type germanium semiconductor, it must be doped with-
(a) indium
(b) phosphorus
(c) arsenic
(d) antimony.
Answer:
(a) indium
Hint:
Only In is a trivalent impurity atom, its doping with germanium produces a p-type semi-conductor.

Question 65.
When arsenic is added as an impurity to silicon, the resulting material is-
(a) n-type conductor
(b) n-type semiconductor
(c) P – type semiconductor
(d) none of these.
Answer:
(b) n-type semiconductor
Hint:
When pentavalent arsenic is doped to silicon, it forms n-type semi – conductor.

Question 66.
In a p-type semiconductor, the majority carriers of current are-
(a) protons
(b) electrons
(c) holes
(d) neutrons.
Answer:
(c) holes

Question 67.
The depletion layer in the p – n junction region is caused by-
(a) drift of holes
(b) diffusion of charge carriers
(c) migration of impurity ions
(d) drift of electrons.
Answer:
(b) diffusion of charge carriers
Hint:
The depletion layer in the p-n junction region is caused by diffusion of charge carriers.

Question 68.
In the depletion region of an unbiased p – n junction diode, there are-
(a) holes
(b) mobile ions
(c) electrons
(d) immobile ions.
Answer:
(d) immobile ions.
Hint:
The depletion layer consists of immobile ions.

Question 69.
In forward bias, the width of potential barrier in a p – n junction adiode.
(a) remain constant
(b) decreases
(c) increases
(d) first (a) then (b).
Answer:
(b) decreases

Question 70.
Reverse bias applied to a junction diode-
(a) lowers the potential barrier
(b) raises the potential barrier
(c) increases the majority carrier current
(d) increases the minority carrier current.
Answer:
(b) raises the potential barrier

Question 71.
Barrier potential of a p – n junction diode does not depend on-
(a) diode design
(b) temperature
(c) forward bias
(d) doping density.
Answer:
(a) diode design
Hint:
Barrier potential depends upon temperature, doping density and forward biasing.

Question 72.
The peak voltage in the output of a half wave diode rectifier fed with a sinusoidal signal without filter is 10 V. The d.c component of the output voltage is-
(a) $\frac { 10 }{ \sqrt { 2V } } $
(b) $\frac { 10 }{ πV }$
(c) 10v
(d) $\frac { 20 }{ πV }$.
Answer:
(b) $\frac { 10 }{ πV }$
Hint:
V_dc = V_m = $\frac { { V }_{ 0 } }{ π } $ = $\frac { 10 }{ π }$ V.

Question 73.
A p-n junction diode can be used as-
(a) condenser
(b) regulator
(c) amplifier
(d) rectifier.
Answer:
(d) rectifier.

Question 74.
Zener diode is used for-
(a) amplification
(b) rectification
(c) stabilisation
(d) producing oscillations in an oscillator.
Answer:
(d) producing oscillations in an oscillator.
Hint:
Zener diode can be used for stabilisation of voltage.

Question 75.
When n-p-n transistor is used as an amplifier, then
(a) electrons move from collector to base
(b) holes move from base to emitter
(c) electrons move from base to collector
(d) electrons move from emitter to base
Answer:
(c) electrons move from base to collector
Hint:
When n-p-n transistor is used an amplifier, the majority carrier electrons move from base to collector.

Question 76.
The correct relationship between the two current gains a and P in a transistor is-
(a) α = $\frac { β }{ 1+β }$
(b) α = $\frac { 1+β }{ β }$
(c) β = $\frac { α }{ 1+α }$
(d) β = $\frac { α }{ α-1 }$.
Answer:
(a) α = $\frac { β }{ 1+β }$
Hint:
β = $\frac { α }{ 1+α }$ (or) β – βα = α ; α = $\frac { β }{ 1+β }$.

Question 77.
The correct relation for a, P for a transistor is-
(a) β = $\frac { 1-α }{ α }$
(b) β = $\frac { α }{ 1-α }$
(c) α = $\frac { β-1 }{ β }$
(d) αβ = 1.
Answer:
(b) β = $\frac { α }{ 1-α }$

Question 78.
For a common base circuit if $\frac {{ I }_{C}}{ { I }_{E} }$ = 0.98, then current gain for common emitter circuit will be-
(a) 49
(b) 98
(c) 4.9
(d) 25.5.
Answer:
(a) 49
Hint:
Here $\frac {{ I }_{C}}{ { I }_{E} }$ = α = 0.98 ; β = $\frac { α }{ 1-α }$ = $\frac { 0.98 }{ 1-0.98 }$ = 49.

Question 79.
Radio waves of constant amplitude can be generated with-
(a) FET
(b) filter
(c) rectifier
(d) oscillator.
Answer:
(d) oscillator.

Question 80.
An oscillator is an amplifier with-
(a) a large gain
(b) negative feedback
(c) positive feedback
(d) no feedback.
Answer:
(c) positive feedback

Question 81.
The output of OR gate is 1
(a) if both inputs are zero
(b) if either or both inputs are 1
(c) only if both inputs are 1
(d) if either input is zero.
Answer:
(b) if either or both inputs are 1

Question 82.
The device that can act as a complete electronic circuit is-
(a) junction diode
(b) integrated circuit
(c) junction transistor
(d) zener diode.
Answer:
(b) integrated circuit

Question 83.
At absolute zero temperature, a semiconductor acts as a/an.
(a) dielectric
(b) conductor
(c) insulator
(d) none of these.
Answer:
(c) insulator

Question 84.
At which temperature, a pure semiconductor behave slightly as a conductor?
(a) low temperature
(b) room temperature
(c) high temperature
(d) both (a) and (b).
Answer:
(b) room temperature

Question 85.
In germanium crystal, the forbidden energy gap in joule is.
(a) 1.6 x 10^-19
(b) zero
(c) 1.12 x 10^-19
(d) 1.76 x 10^-19
Answer:
(c) 1.12 x 10^-19
Hint:
For a germanium crystal,
E_g = 0.7 eV = 0.7 x 1.6 x 10^-19 J = 1.12 x 10^-19J.

Question 86.
In a p-type semiconductor, germanium is doped with.
(a) gallium
(b) boron
(c) aluminium
(d) all of these
Answer:
(d) all of these
Hint:
Ga, B and A1 are all trivalent atoms, they produce p-type semiconductor.

Question 87.
The major carrier of current in a p-type semiconductor will be.
(a) neutrons
(b) protons
(c) electrons
(d) holes.
Answer:
(d) holes.
Hint:
Holes are the major carriers of current in a p-type semiconductor.

Question 88.
Rectification is the process of conversion of
(a) a.c into d.c
(b) low a.c into high a.c
(c) d.c into a.c
(d) low d.c into high d.c
Answer:
(a) a.c into d.c

Question 89.
Which type of gate is represented by the given figure?
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-48
(a) NAND
(b) NOT
(c) AND
(d) OR.
Answer:
(b) NOT
Hint:
When both the inputs of a NAND gate are joined, it functions as a NOT gate.

Question 90.
Which of the following gates can be served as a building block for any digital circuit?
(a) OR
(b) NOT
(c) AND
(d) NAND.
Answer:
(d) NAND.
Hint:
A NAND gate is a universal gate.

Samacheer Kalvi 12th Physics Semiconductor Electronics Short Answer Questions

Question 1.
What are passive and active components.
Answer:
Passive components:
Components that cannot generate power in a circuit.
Active components:
components that can generate power in a circuit.

Question 2.
What are energy band?
Answer:
The band of very large number of closely spaced energy levels in a very small energy range is known as energy band.

Question 3.
What are valence band, conduction band and forbidden energy gap.
Answer:
The energy band formed due to the valence orbitals is called valence band and that formed due to the unoccupied orbitals is called the conduction band. The energy gap between the valence band and the conduction band is called forbidden energy gap.

Question 4.
What are intrinsic semiconductor?
Answer:
A semiconductor in its pure form without impurity is called an intrinsic semiconductor. In intrinsic semiconductors, the number of electrons in the conduction band is equal to the number of holes in the valence band.

Question 5.
What are extrinsic semiconductor?
Answer:
An extrinsic semiconductor is a semiconductor doped by a specific impurity which is able to deeply modify its electrical properties, making it suitable for electronic applications (diodes, transistors etc.) or optoelectronic applications (light emitters and detectors).

Question 6.
What are holes?
Answer:
The vacancy or absense of an electron in the bond of a covalently bonded crystal is called a hole.

Question 7.
What is meant by biasing and bias voltage?
Answer:
Biasing means providing external energy to charge carriers to overcome the barrier potential and make them move in a particular direction. The external voltage applied to the p-n junction is called bias voltage.

Question 8.
What are called forward bias and reverse bias?
Answer:

If the positive terminal of the external voltage source is connected to the p-side and the negative terminal to the n-side, it is called forward bias.
If the positive terminal of the battery is connected to the n-side and the negative potential to the p-side, the junction is said to be reverse biased.

Question 9.
Define knee voltage or threshold voltage or cut-in voltage.
Answer:
At room temperature, a potential difference equal to the barrier potential is required before a reasonable forward current starts flowing across the diode. This voltage is known as threshold voltage or cut-in voltage or knee voltage (V_th).

Question 10.
What is a Rectification?
Answer:
Rectification is the process of converting alternating current into direct current is called rectification.

Question 11.
Define – Efficiency of rectifier.
Answer:
Efficiency (η) is the ratio of the output dc power to the ac input power supplied to the circuit.

Question 12.
What is meant by zener effect?
Answer:
The electric field is strong enough to break or rupture the covalent bonds in the lattice and thereby generating electron-hole pairs. This effect is called Zener effect.

Question 13.
What is a zener diode?
Answer:
A junction diode specially designed to operate only in the reverse breakdown region continuously (without getting damaged) is called a zener diode.

Question 14.
Write down the applications of zener diode.
Answer:
The zener diode can be used as:

Voltage regulators
Peak clippers
Calibrating voltages
Provide fixed reference voltage in a network for biasing
Meter protection against damage from accidental application of excessive voltage.

Question 15.
What is peak inverse voltage (PIV)?
Answer:
The maximum reverse bias that can be applied before entering into the Zener region is called the Peak inverse voltage.

Question 16.
What is Optoelectronic devices?
Answer:
Optoelectronics deals with devices which convert electrical energy into light and light into electrical energy through semiconductors.

Question 17.
Write down the applications of LED’s?
Answer:

Indicator lamps on the front panel of the scientific and laboratory equipments.
Seven-segment displays.
Traffic signals, exit signs, emergency vehicle lighting etc.
Industrial process control, position encoders, bar graph readers.

Question 18.
Write down the applications of photodiodes?
Answer:

Alarm system
Count items on a conveyer belt
Photoconductors
Compact disc players, smoke detectors
Medical applications such as detectors for computed tomography etc.

Question 19.
Write down the applications of solar cell.
Answer:

Solar cells are widely used in calculators, watches, toys, portable power supplies, etc.
Solar cells are used in satellites and space applications
Solar panels are used to generate electricity.

Question 20.
What is a solar cell.
Answer:
A solar cell, also known as photovoltaic cell, converts light energy directly into electricity or electric potential difference by photovoltaic effect.

Question 21.
Write down the applications of Oscillators.
Answer:
Applications of oscillators:

to generate a periodic sinusoidal or non sinusoidal wave forms.
to generate RF carriers.
to generate audio tones
to generate clock signal in digital circuits.
as sweep circuits in TV sets and CRO.

Question 22.
Write down concept of Barkhausen conditions for sustained oscillations.
Answer:
Barkhausen conditions for sustained oscillations
The following condition called Barkhausen conditions should be satisfied for sustained oscillations in the oscillator.

The loop phase shift must be 0° or integral multiples of 2π.
The loop gain must be unity. |Aβ| = 1
Here; A → Voltage gain of the amplifier,
b → feedback ratio; (fraction of the output that is fed back to the input)

Samacheer Kalvi 12th Physics Semiconductor Electronics Long Answer Questions

Question 1.
Explain the classification of materials.
Answer:
Insulators:
The valence band and the conduction band are separated by a large energy gap. The forbidden energy gap is approximately 6 eV in insulators. The gap is very large that electrons from valence band cannot move into conduction band even on the application of strong external electric field or the increase in temperature. Therefore, the electrical conduction is not possible as the free electrons are almost nil and hence these materials are called insulators. Its resistivity is in the range of 10¹¹ – 10¹⁹ Ωm.

Metals:
In metals, the valence band and conduction band overlap. Hence, electrons can move freely into the conduction band which results in a large number of free electrons in the conduction band. Therefore, conduction becomes possible even at low temperatures. The application of electric field provides sufficient energy to the electrons to drift in a particular direction to constitute a current. For metals, the resistivity value lies between 10^-2 and 10^-8 Ωm.

Semiconductors:
In semiconductors, there exists a narrow forbidden energy gap (E_g < 3 eV ) between the valence band and the conduction band. At a finite temperature, thermal agitations in the solid can break the covalent bond between the atoms (covalent bond is formed due to the sharing of electrons to attain stable electronic configuration). This releases some electrons from valence band to conduction band. Since free electrons are small in number, the conductivity of the semiconductors is not as high as that of the conductors. The resistivity value of semiconductors is from 10^-5 to 10⁶ Ωm.

Question 2.
Explain zener diode as a voltage regulator.
Answer:
Zener diode as a voltage regulator:
A Zener diode working in the breakdown region can serve as a voltage regulator. It maintains a constant output voltage even when input voltage V_i or load current I_L varies. Here, in this circuit the input voltage V_i is regulated at a constant voltage, V_z (Zener voltage) at the output represented as V₀ using a Zener diode. The output voltage is maintained constant as long as the input voltage does not fall belowV_z.
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-49
When the potential developed across the diode is greater than V_z ,the diode moves into the Zener breakdown region. It conducts and draws relatively large current through the series resistance R_i. The total current I passing through R_i equals the sum of diode current I_z and load current I_L (I = I_z + I_L) It is to be noted that the total current is always less than the maximum Zener diode current.
Under all conditions V₀ = V_z Thus, output voltage is regulated.

Question 3.
Write down the concept in details of Integrated Chips (IC’s) Integrated Chips
Answer:
An integrated circuit is also referred as an IC or a chip or a microchip. It consists of thousands to millions of transistors, resistors, capacitors, etc. integrated on a small flat piece of semiconductor material that is normally Silicon. Integrated circuits (ICs) are the keystone of modem electronics. With the advancement in technology and the emergence of Very Large Scale Integration (VLSI) era it is possible to fit more aind more transistors on chips of same piece.

ICs have two main advantages over ordinary circuits: cost and performance. The size, speed, and capacity of chips have progressed enormously with the advancement in technology. Computers, mobile phones, and other digital home appliances are now made possible by the small size and low cost of ICs. ICs can function as an amplifier, oscillator, timer, microprocessor and computer memory.

These extremely small ICs can perform calculations and store data using either digital or analog technology. Digital ICs use logic gates, which work only with values of ones and zeros. A low signal sent to a component on a digital IC will result in a value of 0, while a high signal creates a value of 1.

Samacheer Kalvi 12th Physics Semiconductor Electronics Numerical Problems

Question 1.
If the energy of a photon of sodium light (λ = 589 nm) equals the band gap of a semiconductor, calculate the minimum energy required to create hole-electron pair.
Solution:
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-50

Question 2.
In PNP transistor circuit, the collector current is 10 mA. If 90% of the holes reach the collector, find emitter and base currents.
Solution:
Here, I_E = 10 mA
As 90% of the holes reach the collector, so the collector current.
I_C = 90% of I_E
I_C = $\frac { 90 }{ 100 }$ I_E
I_E = $\frac { 100 }{ 90 }$ I_C = $\frac { 100 }{ 90 }$ x 10
I_E ≃ 11mA
Base current, I_B = I_E – I_C = 11 – 10
I_B = 1 mA.

Question 3.
In the circuit, the value of β is 100. Find I_B, V_CE, V_BE and V_BC, when I_C = 1.5 mA. The transistor is in active, cut off or saturation state?
Solution:
β = 100; I_C = 1.5 mA= 1.5 x 10^-3 A, V_CC = 24 V
β = $\frac {{ I }_{ C }}{{ I }_{ B }}$
I_B = $\frac {{ I }_{ C }}{β}$ = $\frac { 1.5\times { 10 }^{ -3 } }{ 100 } $ = 15 μA
To calculate V_CE, We apply Kirchhoff’s rule to loop CEFDC, therefore
V_CC = I_C x 4.7 kΩ + V_CE
24 = 1.5 x 10^-3 x 4.7 10^-3 + V_CE
V_CE = 24 – 7.05 = 16.95 V
Samacheer Kalvi 12th Physics Solutions Chapter 9 Semiconductor Electronics-51
Again, applying Kirchhoff’s rule to loop ABEFDCA, We get,
V_CC = I_B x 220 kΩ + V_BE
V_CC = 15 x 10^-6 x 220 x 10^-3 + V_BE
V_BE= 24 -3.3
V_BE = 20.7 V
Going along loop ABCA, we get
I_B x 220 kΩ + V_BC= I_c x 4.7 kΩ
15 x 10^-6x 220 x 10³ + V_Bc= 1.5 x 10^-3 x 4.7 x 10³V_BC= 7.05 -3.3 = 3.75 V
As V_CE < V_BE, both the junctions are forward biased. So, the transistor is in the saturation state.

Question 4.
A transistor has α = 0.95. If the emitter current is 10 mA, what is (a) the collector current, (b) the base current and (c) gain β?
Solution:
Here, α = 0.95, I_E = 10 mA
(a) α = $\frac {{ I }_{ C }}{{ I }_{ E }}$ ⇒ I_C = αI_E = 0.95 x 10 = 9.5 mA
(b) I_B = I_E – I_C = 10 – 9.5 = 0.5 mA
(c) β = $\frac { α }{ 1-α }$ = $\frac { 0.95 }{ 0.05 }$ = 19.

Question 5.
For a BJT, the common-base current gain α = 0.98 and the collector base junction reverse bias saturation current I_C0= 0.6 μA. This BJT is connected in the common emitter mode and operated in the active region with a base drive current I_B = 20 μA. Find the collector current I_C for this mode of operation.
Solution:
α = 0.98 and I_C0= 0.6 μA
Collector current,
β = $\frac { α }{ 1-α }$ = $\frac { 0.98 }{ 1-0.98 }$ = 49
Thus,
I_C = (49 x 20) + (50 x 0.6) = 980 + 30 = 1010 μA
I_C = 1.01 μA.

Question 6.
An NPN BJT having reverse saturation current I_S = 10^-15 A is biased in the forward active region with V_BE = 700 mV and the current gain (β) may vary from 50 to 150 due to manufacturing variations. What is the maximum emitter current (in μA)
Solution:
I_S = 10^-15 A
V_BE = 700
V_T= 25 mV
β range from 50 to 150
I_C = I₀ e^(V_BE/V_T)
I_E = $\frac { β+1 }{ β }$ I_C
I_E = $\frac { β+1 }{ β }$ I_S e^V_BE/V_T
I_E will be maximum when β is 50
= 1.02 × 10^-15 × e^{700 × 10^-3/25 × 10^-3}
I_E = 1475 μA

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Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics

April 15, 2024

Students those who are preparing for the 12th Physics exam can download this Samacheer Kalvi 12th Physics Book Solutions Questions and Answers for Chapter 8 Atomic and Nuclear Physics from here free of cost. These Tamilnadu State Board Solutions for Class 12th Physics PDF cover all Chapter 8 Atomic and Nuclear Physics Questions and Answers. All these concepts of Samacheer Kalvi 12th Physics Book Solutions Questions and Answers are explained very conceptually as per the board prescribed Syllabus & guidelines.

Tamilnadu Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics

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Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Textual Evaluation Solved

Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Multiple Choice Questions

Question 1.
Suppose an alpha particle accelerated by a potential of V volt is allowed to collide with a nucleus whose atomic number is Z, then the distance of closest approach of alpha particle to the nucleus is
(a) 14.4$\frac { Z }{ V }$ Å
(b) 14.4$\frac { V }{ Z }$ Å
(c) 1.44$\frac { Z }{ V }$ Å
(d) 14.4$\frac { V }{ Z }$ Å
Answer:
(c) 1.44$\frac { Z }{ V }$ Å

Question 2.
In a hydrogen atom, the electron revolving in the fourth orbit, has angular momentum equal to
(a) h
(b) $\frac { h }{ π }$
(c) $\frac { 4h }{ π }$
(d) $\frac { 2h }{ π }$
Answer:
(d) $\frac { 2h }{ π }$
Hint:
Angular momentum of an electron is an integral multiple of $\frac { h }{ 2π }$
According to Bohr atom model,
Angular momentum of an electron mvr = $\frac { nh }{ 2π }$
n = 4^th orbit = $\frac { 4h }{ 2π }$
mvr = $\frac { 2h }{ π }$

Question 3.
Atomic number of H-like atom with ionization potential 122.4 V for n = 1 is
(a) 1
(b) 2
(c) 3
(d) 4
Answer:
(c) 3
Hint:
The ionisation energy of a hydrogen atom is, IE = $\frac {{ 13.6z }^{2}}{{ n }^{2}}$
∴ z² = $\frac{I E \times n^{2}}{13.6}$ = $\frac{122.4 \times(1)^{2}}{13.6}$ = 9

Question 4.
The ratio between the first three orbits of hydrogen atom is
(a) 1 : 2 : 3
(b) 2 : 4 : 6
(c) 1 : 4 : 9
(d) 1 : 3 : 5
Answer:
(c) 1 : 4 : 9
Hint:
E_n = $\frac {{ -13.6×z }^{2}}{{ n }^{2}}$ eV / atom
n = 1; E₁ = 13.6 eV / atom
n = 2; E₂ = 3.4 eV / atom
n = 3; E₃ = 151 eV / atom
The ratio of theree orbits
E₁ : E₂ : E₃ = 13.6 : 3.4 : 1.51
= 1 : 4 : 9

Question 5.
The charge of cathode rays is
(a) positive
(b) negative
(c) neutral
(d) not defined
Answer:
(b) negative

Question 6.
In J.J. Thomson e/m experiment, a beam of electron is replaced by that of muons (particle with same charge as that of electrons but mass 208 times that of electrons). No deflection condition is achieved only if
(a) B is increased by 208 times
(b) B is decreased by 208 times
(c) B is increased by 14.4 times
(d) B is decreased by 14.4 times
Answer:
(c) B is increased by 14.4 times
Hint:
In the condition of no deflection $\frac { e }{ m }$ = $\frac {{ E }^{2}}{{ 2vB }^{2}}$
If m is increased by 208 times then B should be increased $\sqrt { 208 } $ = 14.4 times

Question 7.
The ratio of the wavelengths for the transition from n =2 to n = 1 in Li⁺⁺, He⁺ and H is
(a) 1 : 2 : 3
(b) 1 : 4 : 9
(c) 3 : 2 : 1
(d) 4 : 9 : 36
Answer:
(d) 4 : 9 : 36
Hint:
According to Rydberg formula, the wavelength
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-1

Question 8.
The electric potential between a proton and an electron is given by V = V₀ In $\left( \frac { r }{ { r }_{ 0 } } \right) $, where r₀is a constant. Assume that Bohr atom model is applicable to potential, then variation of radius of n^th orbit r_n with the principal quantum number n is
(a) r_n ∝$\frac { 1 }{ n }$
(b) r_n ∝ n
(c) r_n ∝ $\frac { 1 }{{ n }^{2}}$
(d) r_n ∝ n²
Answer:
(b) r_n ∝ n
Hint:
Electric potential between proton and electron in nth orbit is given as,
V = V₀ In $\left( \frac { { r }_{ n } }{ { r }_{ 0 } } \right) $
Thus the coulomb force |F_c| = e $\left( \frac { { dv } }{ dr } \right) $ = e $\left( \frac { { V }_{ 0 } }{ { r }_{ n } } \right) $
This coulomb force is balance by the centripetal force
$\frac {{ mv }^{2}}{{r}_{n}}$ = e $\left( \frac { { V }_{ 0 } }{ { r }_{ n } } \right) \left( \frac { { dv } }{ dr } \right) $ ⇒ V = $\sqrt { \frac { e{ V }_{ 0 } }{ m } } $
Now from
mvr_n = $\frac { nh }{2π}$
r_n ∝ n

Question 9.
If the nuclear radius of ²⁷ Al is 3.6 fermi, the approximate unclear radius of⁶⁴Cu is
(a) 2.4
(b) 1.2
(c) 4.8
(d) 3.6
Answer:
(c) 4.8
Hint:
$\frac {{ R }_{Al}}{{ R }_{Cu}}$ = $\frac{(27)^{1 / 3}}{(64)^{1 / 3}}$ = $\frac { 3 }{ 4}$
R_cu = $\frac { 4 }{ 3}$ R_Al= $\frac { 4 }{ 3}$ x 3.6 fermi
R_cu = 4.8 fermi

Question 10.
The nucleus is approximately spherical in shape. Then the surface area of nucleus having mass number A varies as
(a) A^2/3
(b) A^4/3
(c) A^1/3
(d) A^5/3
Answer:
(a) A^2/3
Hint:
Volume of nucleus is proportional to mass number 4
$\frac { 4 }{ 3 }$ πR³ ∝ A = R₀ A^1/3
So, πR² = RR₀ A^2/3 ⇒ 4πR² ∝ A^2/3
Surface area is proportional to (mass number)^2/3

Question 11.
The mass of a $_{ 3 }^{ 7 }{ Li }$ nucleus is 0.042 u less than the sum of the masses of all its nucleons. The binding energy per nucleon of $_{ 3 }^{ 7 }{ Li }$ nucleus is nearly
(a) 46 MeV
(b) 5.6 MeV
(c) 3.9 MeV
(d) 23 MeV
Answer:
(b) 5.6 MeV
Hint:
If w = 1 u, C = 3 x 10⁸ ms^-1 then, E = 931 MeV
1 u = 931 Mev
Binding energy = 0. 042 x 931
= 39. 10 MeV
∴ B.E 39.10
Binding energy per nucleon = $\frac { B.E }{ A }$ = $\frac { 39.10 }{ 7 }$ = 5.58 = 5.6 MeV

Question 12.
denotes the mass of the proton and M_n denotes mass of a neutron. A given nucleus of binding energy B, contains Z protons and N neutrons. The mass M (N, Z) of the nucleus is given by(where c is the speed of light)
(a) M (N, Z) = NM_n + ZM_p – Bc²
(b) M (N, Z) = NM_n + ZM_p + Bc²
(c) M (N, Z) = NM_n + ZM_p – B / c²
(d) M (N, Z) = NM_n + ZM_p + B / c²
Answer:
(c) M (N, Z) = NM_n + ZM_p – B / c²
Hint:
Binding energy, B = [ZM_p + NM_n – M (N, Z)] C²
M(N,Z) = ZM_p + NM_n – $\frac { B }{{ C }^{ 2 }}$

Question 13.
A radioactive nucleus (initial mass number A and atomic number Z) emits 2α and 2 positrons. The ratio of number of neutrons to that of proton in the final nucleus will be
(a) $\frac { A-Z-4 }{ Z-2 }$
(b) $\frac { A-Z-2 }{ Z 6 }$
(c) $\frac { A-Z-4 }{ Z-6 }$
(d) $\frac { A-Z-12 }{ Z-4 }$
Answer:
(b) $\frac { A-Z-2 }{ Z 6 }$

Question 14.
The half-life period of a radioactive element A is same as the mean life time of another radioactive element B. Initially both have the same number of atoms. Then
(a) A and B have the same decay rate initially
(b) A and B decay at the same rate always
(c) B will decay at faster rate than A
(d) A will decay at faster rate than B.
Answer:
(c) B will decay at faster rate than A
Hint:
(t_1/2)_A = (t_mean )_B
$\frac { 0.6931 }{{ λ }_{A}}$ = $\frac { 1 }{{ λ }_{B}}$
λ_A = 0.6931 λ_B
λ_A < λ_B

Question 15
A system consists of N₀ nucleus at t = 0. The number of nuclei remaining after half of a half-life (that is, at time t =$\frac { 1 }{ 2 }$ T_{$\frac { 1 }{ 2 }$})
(a) $\frac {{ N }_{0}}{ 2 }$
(b) $\frac {{ N }_{0}}{ √2 }$
(c) $\frac {{ N }_{0}}{ 4 }$
(d) $\frac {{ N }_{0}}{ 8 }$
Answer:
(b) $\frac {{ N }_{0}}{ √2 }$
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-2

Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Short Answer Questions

Question 1.
What are cathode rays?
Answer:
A cathode ray is a stream of electrons that are seen in vaccum tubes. It is called a “cathode ray” because the electrons are being emitted from the negative charged element in the vaccum tube called the cathode.

Question 2.
Write the properties of cathode rays.
Answer:

Cathode rays possess energy and momentum and travel in a straight line with high speed of the order of 10⁷m s^-1
It can be deflected by application of electric and magnetic fields.
When the cathode rays are allowed” to fall on matter, they produce heat.
They affect the photographic plates and also produce fluorescence when they fall on certain crystals and minerals.
When the cathode rays fall on a material of high atomic weight, x-rays are produced.
Cathode rays ionize the gas through which they pass.
The speed of cathode rays is up to( $\frac { 1 }{ 10 }$)^th

Question 3.
Give the results of Rutherford alpha scattering experiment.
Answer:

Most of the alpha particles are undeflected through the gold foil and went straight.
Some of the alpha particles are deflected through a small angle.
A few alpha particles (one in thousand) are deflected through the angle more than 90°.
Very few alpha particles returned back (back scattered) -that is, deflected back by 180°.

Question 4.
Write down the postulates of Bohr atom model.
Answer:
Postulates of Bohr atom model:

The electron in an atom moves around nucleus in circular orbits under the influence of Coulomb electrostatic force of attraction. This Coulomb force gives necessary centripetal force for the electron to undergo circular motion.
Electrons in an atom revolve around the nucleus only in certain discrete orbits called stationary orbits where it does not radiate electromagnetic energy. Only those discrete orbits allowed are stable orbits.

Question 5.
What is meant by excitation energy?
Answer:
The energy required to excite an electron from lower energy state to any higher energy state is known as excitation energy.

Question 6.
Define the ionization energy and ionization potential.
Answer:
The ionization energy and ionization potential are:

Ionization energy: The minimum energy required to remove an electron from an atom in the ground state is known as binding energy or ionization energy.
Ionization potential: Ionization potential is defined as ionization energy per unit charge.

Question 7.
Write down the draw backs of Bohr atom model.
Answer:
Limitations of Bohr atom model:
The following are the drawbacks of Bohr atom model:

Bohr atom model is valid only for hydrogen atom or hydrogen like-atoms but not for complex atoms.
When the spectral lines are closely examined, individual lines of hydrogen spectrum is accompanied by a number of faint lines. These are often called fine structure. This is not explained by Bohr atom model.
Bohr atom model fails to explain the intensity variations in the spectral lines.
The distribution of electrons in atoms is not completely explained by Bohr atom model.

Question 8.
What is distance of closest approach?
Answer:
The minimum distance between the centre of the nucleus and the alpha particle just before it gets reflected back through 180° is defined as the distance of closest approach r₀ (also known as contact distance).

Question 9.
Define impact parameter.
Answer:
The impact parameter is defined as the perpendicular distance between the centre of the gold nucleus and the direction of velocity vector of alpha particle when it is at a large distance.

Question 10.
Write a general notation of nucleus of element X. What each term denotes?
Answer:
The nucleus of any element, we use the following general notation $_{ Z }^{ A }X$
where X is the chemical symbol of the element, A is the mass number and Z is the atomic number.

Question 11.
What is isotope? Give an example.
Answer:
Isotopes are atoms of the same element having same atomic number Z, but different mass number A. For example, hydrogen has three isotopes and they are represented as $_{ 1 }^{ 1 }H$ (hydrogen), $_{ 1 }^{ 2 }H$ (deuterium),and $_{ 1 }^{ 3 }H$ (tritium).

Question 12.
What is isotone? Give an example.
Answer:
Isotones are the atoms of different elements having same number of neutrons. $_{ 5 }^{ 12 }B$ and $_{ 6 }^{ 13 }B$ are examples of isotones which 7 neutrons.

Question 13.
What is isobar? Give an example.
Answer:
1. Isobar: Isobars are the atoms of different elements having the same mass number A, but different atomic number Z.
2. For example $_{ 16 }^{ 40 }S$, $_{ 17 }^{ 40 }Cl$, $_{ 18 }^{ 40 }Ar$,$_{ 19 }^{ 40 }K $ and $_{ 20 }^{ 40 }Ca$ are isobars having same mass number 40 and different atomic number.

Question 14.
Define atomic mass unit u.
Answer:
One atomic mass unit (u) is defined as the 1/12^th of the mass of the isotope of carbon $_{ 6 }^{ 12 }C$.

Question 15.
Show that nuclear density is almost constant for nuclei with Z > 10.
Answer:
Nuclear density,
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-3
The expression shows that the nuclear density is independent of the mass number A. In other words, all the nuclei (Z > 10) have the same density and it is an important characteristics of the nuclei.

Question 16.
What is mass defect?
Answer:
The mass of any nucleus is always less than the sum of the mass of its individual constituents. The difference in mass Am is called mass defect.
∆m = (Zm_p + Nm_n) – M.

Question 17.
What is binding energy of a nucleus? Give its expression.
Answer:
when Z protons and N neutrons combine to form a nucleus, mass equal to mass defect disappears and the corresponding energy is released. This is called the binding energy of the nucleus (BE) and is equal to (∆m) c².
BE = (Zm_p + Nm_n – M ) c²

Question 18.
Calculate the energy equivalent of 1 atomic mass unit.
Answer:
We take, m = 1 amu = 1.66 x 10^-27 kg
c = 3 x 10⁸ms^-1
Then, E = mc² = 1.66 x 10^-27 x (3 x 10⁸)² J
$\frac{1.66 \times 10^{-27} \times\left(3 \times 10^{8}\right)^{2}}{1.6 \times 10^{-19}} e \mathrm{V}$
E ≈ 981 MeV
∴ 1 amu = 931 MeV.

Question 19.
Give the physical meaning of binding energy per nucleon.
Answer:
The average binding energy per nucleon is the energy required to separate single nucleon from the particular nucleus.

Question 20.
What is meant by radioactivity?
Answer:
The phenomenon of spontaneous emission of highly penetrating radiations such as α, β and γ rays by an element is called radioactivity.

Question 21.
Give the symbolic representation of alpha decay, beta decay and gamma decay.
Answer:
1. Alpha decay:
The alpha decay process symbolically in the following way
$_{ Z }^{ A }X$ → $_{ Z-2 }^{ A-4 }Y$ + $_{ 2 }^{ 4 }He$

2. Beta decay:
β decay is represented by $_{ Z }^{ A }X$ → $_{ Z-1 }^{ A }Y$ +e⁺ + v

3. Gamma decay:
The gamma decay is given by $_{ Z }^{ A }{{ X }^{ * }}$ → $_{ Z }^{ A }X$ + gamma (γ ) rays

Question 22.
In alpha decay, why the unstable nucleus emits $_{ 2 }^{ 4 }He$ He nucleus? Why it does not emit four separate nucleons?
Answer:
After all $_{ 2 }^{ 4 }He$ He consists of two protons and two neutrons. For example, if $_{ 92 }^{ 238 }U$ nucleus decays into $_{ 90 }^{ 234 }U$ Th by emitting four separate nucleons (two protons and two neutrons), then the disintegration energy Q for this process turns out to be negative. It implies that the total mass of products is greater than that of parent ($_{ 92 }^{ 238 }U$) nucleus. This kind of process cannot occur in nature because it would violate conservation of energy. In any decay process, the conservation of energy, conservation of linear momentum and conservation of angular momentum must be obeyed.

Question 23.
What is mean life of nucleus? Give the expression.
Answer:
The mean life time of the nucleus is the ratio of sum or integration of life times of all nuclei to the total number nuclei present initially.
The expression for mean life time, τ = $\frac { 1 }{ λ }$.

Question 24.
What is half-life of nucleus? Give the expression.
Answer:
The half-life T_1/2 is defined as the time required for the number of atoms initially present to reduce to one half of the initial amount.
T_1/2 = $\frac { In 2 }{ λ }$ = $\frac { 0.6931 }{ λ }$.

Question 25.
What is meant by activity or decay rate? Give its unit.
Answer:
The activity (R) or decay rate is defined as the number of nuclei decayed per second and it is denoted as R = $\left| \frac { dN }{ dt } \right| $
The SI unit of activity R is Becquerel.

Question 26.
Define curie.
Answer:
One curie was defined as number of decays per second in 1 g of radium and it is equal to 3.7 x 10¹⁰ decays/s.

Question 27.
What are the constituent particles of neutron and proton?
Answer:
Protons and neutrons are Baryon which are made up of three Quarks. According to quark model, proton is made up of two up quarks and one down quark and neutron is made up of one up quark and two down quarks.

Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Long Answer Questions

Question 1.
Explain the J.J. Thomson experiment to determine the specific charge of electron.
Answer:
In 1887, J. J. Thomson made remarkable improvement in the scope of study of gases in discharge tubes. In the presence of electric and magnetic fields, the cathode rays are deflected. By the variation of electric and magnetic fields, mass normalized charge or the specific charge (charge per unit mass) of the cathode rays is measured.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-4
A highly evacuated discharge tube is used and cathode rays (electron beam) produced at cathode are attracted towards anode disc A. Anode disc is made with pin hole in order to allow only a narrow beam of cathode rays. These cathode rays are now allowed to pass through the parallel metal plates, maintained at high voltage.

Further, this gas discharge tube is kept in between pole pieces of magnet such that both electric and magnetic fields are perpendicular to each other. When the cathode rays strike the screen, they produce scintillation and hence bright spot is observed. This is achieved by coating the screen with zinc sulphide.

(i) Determination of velocity of cathode rays:
For a fixed electric field between the plates, the magnetic field is adjusted such that the cathode rays (electron beam) strike at the original position O.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-5
This means that the magnitude of electric force is balanced by the magnitude of force due to magnetic field. Let e be the charge of the cathode rays, then
eE = eBv
⇒ v = $\frac { E }{ B }$ ….. (1)

(ii) Determination of specific charge:
Since the cathode rays (electron beam) are accelerated from cathode to anode, the potential energy of the electron beam at the cathode is converted into kinetic energy of the electron beam at the anode. Let V be the potential difference between anode and cathode, then the potential energy is eV. Then from law of conservation of energy,
eV = $\frac { 1 }{ 2 }$ mv² ⇒ $\frac { e }{ m }$ = $\frac {{ v }^{ 2 }}{ 2V }$
Substituting the value of velocity from equation (1), we get
$\frac { e }{ m }$ = $\frac { 1 }{ 2V }$ = $\frac {{ E }^{ 2 }}{{ B }^{ 2 }}$ …… (2)
Substituting the values of E, B and V, the specific charge can be determined as
$\frac { e }{ m }$ = 1.7 x 10¹¹ C kg^-1

(iii) Deflection of charge only due to uniform electric field:
When the magnetic field is turned off, the deflection is only due to electric field. The deflection in vertical direction is due to the electric force.
F_e = eE ….. (3)
Let m be the mass of the electron and by applying Newton’s second law of motion, acceleration of the electron is
a_e = $\frac { 1 }{ m }$ F_e …. (4)
Substituting equation (4) in equation (3),
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-6
a_e = $\frac { 1 }{ m }$ eE = $\frac { e }{ m }$ E
Lety be the deviation produced from original position on the screen. Let the initial upward velocity of cathode ray be u = 0 before entering the parallel electric plates. Let t be the time taken by the cathode rays to travel in electric field. Let t be the length of one of the plates, then the time taken is
t = $\frac { 1 }{ v }$ ….. (5)
Hence, the deflection y’ of cathode rays is (note : u = 0 and a_e = $\frac { e }{ m }$ E)
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-7
Therefore, the deflection y on the screen is
y ∝ y’ ⇒ y = Cy’
where C is proportionality constant which depends on the geometry of the discharge tube and substituting y’ value in equation (6), we get
y = C$\frac { 1 }{ 2 }$ $\frac { e }{ m }$ $\frac{l^{2} B^{2}}{E}$ …… (7)
Rerranging equation (7) as
$\frac { e }{ m }$ = $\frac{2 y E}{C l^{2} B^{2}}$ ……. (8)
Substituting the values on RHS, the value of specific charge is calculated as
$\frac { e }{ m }$ = 1.7 x 10¹¹ Ckg^-1

(iv) Deflection of charge only due to uniform magnetic field:
Suppose that the electric field is switched off and only the magnetic field is switched on. Now the deflection occurs only due to magnetic field. The force experienced by the electron in uniform magnetic field applied perpendicular to its path is
F_m = evB (in magnitude)
Since this force provides the centripetal force, the electron beam undergoes a semicircular path. Therefore, we can equate F_m to centripetal force
$\frac {{ mv }^{2}}{ R }$
F_m = evB = m $\frac {{ v }^{2}}{ R }$
where v is the velocity of electron beam at the point where it enters the magnetic field and R is the radius of the circular path traversed by the electron beam.
eB = m $\frac { v }{ R }$ ⇒ $\frac { e }{ m }$ = $\frac { v }{ BR }$ …… (9)
Further, substituting equation (1) in equation (9), we get
$\frac { e }{ m }$ = $\frac{E}{B^{2} R}$ ……. (10)
By knowing the values of electric field, magnetic field and the radius of circular path, the value of specific charge$\left( \frac { e }{ m } \right) $ can be calculated.

Question 2.
Discuss the Millikan’s oil drop experiment to determine the charge of an electron.
Answer:
Millikan’s oil drop experiment is another important experiment in modem physics which is used to determine one of the fundamental constants of nature known as charge of an electron. By adjusting electric field suitably, the motion of oil drop inside the chamber can be controlled – that is, it can be made to move up or down or even kept balanced in the field of view for sufficiently long time.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-8
1. The apparatus consists of two horizontal circular metal plates A and B each with diameter around 20 cm and are separated by a small distance 1.5 cm. These two parallel plates are enclosed in a chamber with glass walls. Further, plates A and B are given a high potential difference around 10 kV such that electric field acts vertically downward.

2. A small hole is made at the centre of the upper plate A and atomizer is kept exactly above the hole to spray the liquid. When a fine droplet of highly viscous liquid (like glycerine) is sprayed using atomizer, it falls freely downward through the hole of the top plate only under the influence of gravity.

3. Few oil drops in the chamber can acquire electric charge (negative charge) because of friction with air or passage of x-rays in between the parallel plates. Further the chamber is illuminated by light which is passed horizontally and oil drops can be seen clearly using microscope placed perpendicular to the light beam. These drops can move either upwards or downward.

4. Let m be the mass of the oil drop and q be its charge. Then the forces acting on the droplet are
(a) gravitational force Fg = mg
(b) electric force Fe = qE
(c) buoyant force Fb

(a) Determination of radius of the droplet: When the electric field is switched off, the oil drop accelerates downwards. Due to the presence of air drag forces, the oil drops easily attain its terminal velocity and moves with constant velocity. This velocity can be carefully measured by nothing down the time taken by the oil drop to fall through a predetermined distance. The free body diagram of the oil drop), we note that viscous force and buoyant force balance the gravitational force.
Let the gravitational force acting on the oil drop (downward) be Fg = mg.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-9
Let us assume that oil drop to be spherical in shape. Let ρ be the density of the oil drop, and r be the radius of the oil drop, then the mass of the oil drop can be expressed in terms of its density as

The gravitational force can be written in terms of density as
F_g = mg ⇒ F_g = ρ $\left( \frac { 4 }{ 3 } \pi { r }^{ 3 } \right) $g
Let σ be the density of the air, the upthrust force experienced by the oil drop due to displaced air is
F_b = σ $\left( \frac { 4 }{ 3 } \pi { r }^{ 3 } \right) $g
Once the oil drop attains a terminal velocity υ, the net downward force acting on the oil drop is equal to the viscous force acting opposite to the direction of motion of the oil drop. From Stokes law, the viscous force on the oil drop is
F_r = 6πr vη
From the free body diagram as shown in Figure (a), the force balancing equation is F_g = F_b + F_v
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-11
Thus, equation (1) gives the radius of the oil drop.

(b) Determination of electric charge: When the electric field is switched on, charged oil drops experience an upward electric force (qE). Among many drops, one particular drop can be chosen in the field of view of microscope and strength of the electric field is adjusted to make that particular drop to be stationary. Under these circumstances, there will be no viscous force acting on the oil drop. Then, from the free body diagram, the net force acting on the oil droplet is
F_e = F_b + F_g
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Substituting equation (1) in equation (2), we get

Millikan repeated this experiment several times and computed the charges on oil drops. He found that the charge of any oil drop can be written as integral multiple of a basic value, -1.6 x 10^-19C, which is nothing but the charge of an electron.

Question 3.
Derive the energy expression for hydrogen atom using Bohr atom model.
Answer:
The energy of an electron in the n^th orbit
Since the electrostatic force is a conservative force, the potential energy for the n^th orbit is
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-14
The kinetic energy for the n^th orbit is
KE_n = $\frac { 1 }{ 2 }$ ${ mv }_{ n }^{ 2 }$ $\frac{m e^{4}}{8 \varepsilon_{0}^{2} h^{2}}$ $\frac{Z^{2}}{n^{2}}$This implies that U_n = -2 KE_n. Total energy in the n^th orbit is
E_n = kE_n + U_n = KE_n – 2KE_n = – KE_n
E_n = $\frac{m e^{4}}{8 \varepsilon_{0}^{2} h^{2}}$ $\frac{Z^{2}}{n^{2}}$
For hydrogen (Z = 1),
E_n = $\frac{m e^{4}}{8 \varepsilon_{0}^{2} h^{2}}$ $\frac { 1 }{{ n }^{ 2 }}$ joule ….. (1)
where n stands for principal quantum number. The negative sign in equation (1) indicates that the electron is bound to the nucleus.

Substituting the values of mass and charge of an electron (m and e), permittivity’ of free space ε₀and Planck’s constant h and expressing in terms of eV, we get
E_n = -13.6 $\frac { 1 }{{ n }^{ 2 }}$ eV
For the first orbit (ground state), the total energy of electron is E₁ = – 13.6 eV. For the second orbit (first excited state), the total energy of electron is E₂ = -3.4 eV. For the third orbit (second excited state), the total energy of electron is E₃ = -1.51 eV and so on.

Notice that the energy of the first excited state is greater than the ground state, second excited state is greater than the first excited state and so on. Thus, the orbit which is closest to the nucleus (r₁) has lowest energy (minimum energy compared with other orbits). So, it is often called ground state energy (lowest energy state). The ground state energy of hydrogen (-13.6 eV ) is used as a unit of energy called Rydberg (1 Rydberg = -13.6 eV). The negative value of this energy is because of the way the zero of the potential energy is defined. When the electron is taken away to an infinite distance (very far distance) from nucleus, both the potential energy and kinetic energy terms vanish and hence the total energy also vanishes.

Question 4.
Discuss the spectral series of hydrogen atom.
Answer:
The spectral lines of hydrogen are grouped in separate series. In each series, the distance of separation between the consecutive wavelengths decreases from higher wavelength to the lower wavelength, and also wavelength in each series approach a limiting value known as the series limit. These series are named as Lyman series, Balmer series, Paschen series, Brackett series, Pfund series, etc. The wavelengths of these spectral lines perfectly agree with the equation derived from Bohr atom model.
$\frac { 1 }{ λ }$ R $\left(\frac{1}{n^{2}}-\frac{1}{m^{2}}\right)$ = $\bar { v } $ … (1)
where $\bar { v } $ is known as wave number which is inverse of wavelength, R is known as Rydberg constant whose value is 1.09737 x 10⁷ m^-1 and m and n are positive integers such that m > n. The various spectral series are discussed below:

(a) Lyman series:
Put n = 1 and m = 2, 3, 4 …..in equation (1). The wave number or wavelength of spectral lines of Lyman series which lies in ultra-violet region is
$\bar { v } $ $\frac { 1 }{ λ }$ R $\left(\frac{1}{n^{2}}-\frac{1}{m^{2}}\right)$ = $\bar { v } $

(b) Balmer series:
Put n = 2 and m = 3, 4, 5 …. in equation (1). The wave number or wavelength of spectral lines of Balmer series which lies in visible region is
$\bar { v } $ $\frac { 1 }{ λ }$ R $\left(\frac{2}{n^{2}}-\frac{1}{m^{2}}\right)$ = $\bar { v } $

(c) Paschen series:
Put n = 3 and m = 4, 5, 6…. in equation (1). The wave number or wavelength of spectral lines of Paschen series which lies in infra-red region (near IR) is
$\bar { v } $ $\frac { 1 }{ λ }$ R $\left(\frac{3}{n^{2}}-\frac{1}{m^{2}}\right)$ = $\bar { v } $

(d) Brackett series:
Put n = 4 and m = 5, 6, 7 ….in equation (1). The wave number or wavelength of spectral lines of Brackett series which lies in infra-red region (middle IR) is
$\bar { v } $ $\frac { 1 }{ λ }$ R $\left(\frac{4}{n^{2}}-\frac{1}{m^{2}}\right)$ = $\bar { v } $

(e) Pfund series:
Put n = 5 and m = 6, 7, 8 …. in equation (1). The wave number or wavelength of spectral lines of Pfund series which lies in infra-red region (far IR) is
$\bar { v } $ $\frac { 1 }{ λ }$ R $\left(\frac{5}{n^{2}}-\frac{1}{m^{2}}\right)$ = $\bar { v } $

Question 5.
Explain the variation of average binding energy with the mass number by graph and discuss its features.
Answer:
We can find the average binding energy per nucleon $\overline { BE } $. It is given by
$\overline { BE } $ = $\frac{\left[Z m_{H}+N m_{n}-M_{\mathrm{A}}\right] c^{2}}{\mathrm{A}}$
The average binding energy per nucleon is the energy required to separate single nucleon from the particular nucleus. $\overline { BE } $ is plotted against A of all known nuclei.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-15
Important inferences from of the average binding energy curve:

(i) The value of $\overline { BE } $ rises as the mass number increases until it reaches a maximum value of 8.8 MeV for A = 56 (iron) and then it slowly decreases.

(ii) The average binding energy per nucleon is about 8.5 MeV for nuclei having mass number between A = 40 and 120. These elements are comparatively more stable and not radioactive.

(iii) For higher mass numbers, the curve reduces slowly and BE for uranium is about 7.6 MeV. They are unstable and radioactive.
If two light nuclei with A < 28 combine with a nucleus with A < 56, the binding energy per nucleon is more for final nucleus than initial nuclei. Thus, if the lighter elements combine to produce a nucleus of medium value A, a large amount of energy will be released. This is the basis of nuclear fusion and is the principle of the hydrogen bomb.

(iv) If a nucleus of heavy element is split (fission) into two or more nuclei of medium value A, the energy released would again be large. The atom bomb is based on this principle and huge energy of atom bombs comes from this fission when it is uncontrolled.

Question 6.
Explain in detail the nuclear force.
Answer:
Nucleus contains protons and neutrons. From electrostatics, we leamt that like charges repel each other. In the nucleus, the protons are separated by a distance of about a few Fermi (1 0^-15 m), they must exert on each other a very strong repulsive force. For example, the electrostatic repulsive force between two protons separated by a distance 10^-15 m
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-16
The acceleration experienced by a proton due to the force of 230 N is

This is nearly 1028 times greater than the acceleration due to gravity. So if the protons in the nucleus experience only the electrostatic force, then the nucleus would fly apart in an instant. From this observation, it was concluded that there must be a strong attractive force between protons to overcome the repulsive Coulomb’s force. This attractive force which holds the nucleus together is called strong nuclear force. A few properties of strong nuclear force are

(i) The strong nuclear force is of very short range, acting only up to a distance of a few Fermi. But inside the nucleus, the repulsive Coulomb force or attractive gravitational forces between two protons are much weaker than the strong nuclear force between two protons. Similarly, the gravitational force between two neutrons is also much weaker than strong nuclear force between the neutrons. So nuclear force is the strongest force in nature.

(ii) The strong nuclear force is attractive and acts with an equal strength between proton-proton, proton-neutron, and neutron – neutron.

(iii) Strong nuclear force does not act on the electrons. So it does not alter the chemical properties of the atom.

Question 7.
Discuss the alpha decay process with example.
Answer:
When unstable nuclei decay by emitting an α-particle ($_{ 2 }^{ 4 }{ He }$ nucleus), it loses two protons and two neutrons. As a result, its atomic number Z decreases by 2, the mass number decreases by 4. We write the alpha decay process symbolically in the following way
$_{ Z }^{ A }{ X }$ → $_{ Z-2 }^{ A-4 }{ Y}$ +$_{ 2 }^{ 4 }{ He }$
Here X is called the parent nucleus and Y is called the daughter nucleus.

Example:
Decay of Uranium $_{ 92 }^{ 238 }{ U }$ to thorium $_{ 92 }^{ 234 }{ Th }$with the emission of $_{ 2 }^{ 4 }{ He }$ nucleus (α-particle)
$_{ 92 }^{ 238 }{ U }$ → $_{ 92 }^{ 234 }{ Th }$ + $_{ 2 }^{ 4 }{ He }$
As already mentioned, the total mass of the daughter nucleus and $_{ 2 }^{ 4 }{ He }$ nucleus is always less than that of the parent nucleus. The difference in mass Q = (∆m_x – m_y – m_α) is released as energy called disintegration energy Q and is given by Q = (∆m_x – m_y – m_α) c²

Note that for spontaneous decay (natural radioactivity) Q > 0. In alpha decay process, the disintegration energy is certainly positive (Q > 0). In fact, the disintegration energy Q is also the net kinetic energy gained in the decay process or if the parent nucleus is at rest, Q is the total kinetic energy of daughter nucleus and the 2 He nucleus. Suppose Q < 0, then the decay process cannot occur spontaneously and energy must be supplied to induce the decay.

Question 8.
Discuss the beta decay process with examples.
Answer:
In beta decay, a radioactive nucleus emits either electron or positron. If electron (e^–) is emitted, it is called β^– decay and if positron (e⁺) is emitted, it is called p+ decay. The positron is an anti-particle of an electron whose mass is same as that of electron and charge is opposite to that of electron – that is, +e. Both positron and electron are referred to as beta particles.

1. β^– decay:
In β^– decay, the atomic number of the nucleus increases by one but mass number remains the same. This decay is represented by
$_{ Z }^{ A }{ X }$ → $_{ Z+12 }^{ A }{ Y}$ + e^– + $\bar { v } $ …(1)
It implies that the element X becomes Y by giving out an electron and antineutrino ($\bar { v } $). In otherwords, in each β^– decay, one neutron in the nucleus of X is converted into a proton by emitting an electron (e^–) and antineutrino. It is given by
n → p + e^– + $\bar { v } $
Where p -proton, $\bar { v } $ -antineutrino. Example: Carbon ($_{ 6 }^{ 14 }{ C }$) is converted into nitrogen ($_{ 7 }^{ 14 }{ N }$) through β- decay.
$_{ 6 }^{ 14 }{ C }$ → $_{ 7 }^{ 14 }{ N }$ + e^– + $\bar { v } $

2. β⁺ decay:
In p+ decay, the atomic number is decreased by one and the mass number remains the same. This decay is represented by
$_{ Z }^{ A }{ X }$ → $_{ Z-12 }^{ A }{ Y}$ + e⁺ + v
It implies that the element X becomes Y by giving out an positron and neutrino (v). In otherwords, for each β⁺ decay, a proton in the nucleus of X is converted into a neutron by emitting a positron (e⁺) and a neutrino. It is given by
p → n + e⁺ + v

However a single proton (not inside any nucleus) cannot have β⁺ decay due to energy conservation, because neutron mass is larger than proton mass. But a single neutron (not inside any nucleus) can have β^– decay.
Example: Sodium ($_{ 11 }^{ 23 }{ Na }$) is converted into neon ($_{ 10 }^{ 22 }{ Ne }$) decay.
$_{ 11 }^{ 23 }{ Na }$ → $_{ 10 }^{ 22 }{ Ne }$ + e⁺ + v

Question 9.
Discuss the gamma decay process with example.
Answer:
In a and p decay, the daughter nucleus is in the excited state most of the time. The typical life time of excited state is approximately 10^-11 s. So this excited state nucleus immediately returns to the ground state or lower energy state by emitting highly energetic photons called 7 rays. In fact, when the atom is in the excited state, it returns to the ground state by emitting photons of energy in the order of few eV. But when the excited state nucleus returns to its ground state, it emits a highly energetic photon (γ rays) of energy in the order of MeV. The gamma decay is given by
$_{ Z }^{ A }{ { X }^{ * } }$ → $_{ Z }^{ A }{ X}$ + gamma (γ) rays
Here the asterisk (*) means excited state nucleus. In gamma decay, there is no change in the mass number or atomic number of the nucleus.
Boron ($_{ 5 }^{ 12 }{ B }$) has two beta decay modes:

(i) it undergoes beta decay directly into ground state carbon by emitting an electron of maximum of energy 13.4 MeV.

(ii) it undergoes beta decay to an excited state of carbon ($_{ 6 }^{ 12 }{{ C}^{ * }}$) by emitting an electron of maximum energy 9.0 MeV followed by gamma decay to ground state by emitting a photon of energy 4.4 MeV.
It is represented by
$_{ 5 }^{ 12 }{ B }$ → $_{ 6 }^{ 12 }{ C }$ + e⁺ + $\bar { v } $
$_{ 6 }^{ 12 }{{ C }^{ * }}$ → $_{ 6 }^{ 12 }{ C }$ + γ

Question 10.
Obtain the law of radioactivity.
Answer:
Law of radioactive decay:
At any instant t, the number of decays per unit time, called rate of decay $\left( \frac { dN }{ dt } \right) $ is proportional to the number of nuclei (N) at the same instant.
$\frac { dN }{ dt } $ ∝ N
By introducing a proportionality constant, the relation can be written as
$\frac { dN }{ dt } $ = -λN …… (1)
Here proportionality constant λ is called decay constant which is different for different radioactive sample and the negative sign in the equation implies that the N is decreasing with time. By rewriting the equation (1), we get
dN = -λNdt …… (2)
Here dN represents the number of nuclei decaying in the time interval dt. Let us assume that at time t =0 s, the number of nuclei present in the radioactive sample is N₀. By integrating the equation (2), we can calculate the number of undecayed nuclei N at any time t. From equation (2), we get
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-18
Taking exponentials on both sides, we get
N = N₀ e^-λt ….. (4)
[Note: e^Inx = e^y ⇒ x = e^y]
Equation (4) is called the law of radioactive decay. Here N denotes the number of undecayed nuclei present at any time t and N₀ denotes the number of nuclei at initial time t = 0. Note that the number of atoms is decreasing exponentially over the time. This implies that the time taken for all the radioactive nuclei to decay will be infinite. Equation (4) is plotted.
We can also define another useful quantity called activity (R) or decay rate which is the number of nuclei decayed per second and it is denoted as R = $\left| \frac { dN }{ dt } \right| $.
Note: that activity R is a positive quantity. From equation (4), we get
R = $\left| \frac { dN }{ dt } \right| $ = λ N₀e^-λt ….. (5)
R = R₀e^-λt ….. (6)
Where R = λ N₀
The equation (6) is also equivalent to radioactive law of decay. Here R₀ is the activity of the sample at t = 0 and R is the activity of the sample at any time t. From equation (6), activity also shows exponential decay behavior. The activity R also can be expressed in terms of number of undecayed atoms present at any time t. From equation (6), since N = N₀e^-λtwe write
R = λ N …… (7)
Equation (4) implies that the activity at any time t is equal to the product of decay constant and number of undecayed nuclei at the same time t. Since N decreases over time, R also decreases.

Question 11.
Discuss the properties of neutrino and its role in beta decay.
Answer:
Neutrino:
Initially, it was thought that during beta decay, a neutron in the parent nucleus is converted to the daughter nuclei by emitting only electron as given by
$_{ Z }^{ A }{ X }$ → $_{ Z+1 }^{ A }{ X}$ Y+e^–

1. But the kinetic energy of electron coming out of the nucleus did not match with the experimental results. In alpha decay, the alpha particle takes only certain allowed discrete energies whereas in beta decay, it was found that the beta particle (i.e, electron) have a continuous range of energies.

2. But the conservation of energy and momentum gives specific single values for electron energy and the recoiling nucleus Y. It seems that the conservation of energy, momentum are violated and could not be explained why energy of beta particle have continuous range of values. So beta decay remained as a puzzle for several years.

3. After a detailed theoretical and experimental study, in 1931 W. Pauli proposed a third particle which must be present in beta decay to carry away missing energy and momentum. Fermi later named this particle the neutrino (little neutral one) since it has no charge, have very little mass.

4. For many years, the neutrino (symbol v , Greek nu) was hypothetical and could not be verified experimentally. Finally, the neutrino was detected experimentally in 1956 by Fredrick Reines and Clyde Cowan. Later Reines received Nobel prize in physics in the year 1995 for his discovery.
The neutrino has the following properties

It has zero charge
It has an antiparticle called anti-neutrino.
Recent experiments showed that the neutrino has very tiny mass.
It interacts very weakly with the matter. Therefore, it is very difficult to detect. In fact, in every second, trillions of neutrinos coming from the sun are passing through our body without any interaction.

Question 12.
Explain the idea of carbon dating.
Answer:
Carbon dating:
1. The interesting application of beta decay is radioactive dating or carbon dating. Using this technique, the age of an ancient object can be calculated. All living organisms absorb carbon dioxide (CO₂) from air to synthesize organic molecules. In this absorbed CO₂, the major part is $_{ 6 }^{ 12 }{ C }$ and very small fraction (1.3 x 10^-12) is radioactive $_{ 6 }^{ 14 }{ C }$ whose half-life is 5730 years.
Carbon-14 in the atmosphere is always decaying but at the same time, cosmic rays from outer space are continuously bombarding the atoms in the atmosphere which produces $_{ 6 }^{ 14 }{ C }$. So the continuous production and decay of $_{ 6 }^{ 14 }{ C }$ in the atmosphere keep the ratio of
$_{ 6 }^{ 14 }{ C }$ to $_{ 6 }^{ 12 }{ C }$ always constant.

2. Since our human body, tree or any living organism continuously absorb CO₂ from the atmosphere, the ratio of $_{ 6 }^{ 14 }{ C }$ to $_{ 6 }^{ 12 }{ C }$ in the living organism is also nearly constant. But when the organism dies, it stops absorbing C₂.

3. Since $_{ 6 }^{ 14 }{ C }$ starts to decay, the ratio of $_{ 6 }^{ 14 }{ C }$ to $_{ 6 }^{ 12 }{ C }$ in a dead organism or specimen decreases over the years. Suppose the ratio of $_{ 6 }^{ 14 }{ C }$ to $_{ 6 }^{ 14 }{ C }$ in the ancient tree pieces excavated is known, then the age of the tree pieces can be calculated.

Question 13.
Discuss the process of nuclear fission and its properties.
Answer:
1. When uranium nucleus is bombarded with a neutron, it breaks up into two smaller nuclei of comparable masses with the release of energy.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-19

2. The process of breaking up of the nucleus of a heavier atom into two smaller nuclei with the release of a large amount of energy is called nuclear fission.

3. The fission is accompanied by the release of neutrons. The energy that is released in the nuclear fission is of many orders of magnitude greater than the energy released in chemical reactions.

4. Uranium undergoes fission reaction in 90 different Neutrons ways. The most common fission reactions of $_{ 92 }^{ 235 }{ U }$ nuclei are shown here.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-20

5. Here Q is energy released during the decay of each uranium nuclei. When the slow neutron is absorbed by the uranium nuclei, the mass number increases by one and goes to an excited state $_{ 92 }^{ 236 }{{ U}^{ * }}$. But this excited state does not last longer than 10^-12s and decay into two daughter nuclei along with 2 or 3 neutrons. From each reaction, on an average, 2.5 neutrons are emitted.

Question 14.
Discuss the process of nuclear fusion and how energy is generated in stars.
Answer:
Nuclear Fusion:
1. When two or more light nuclei (A < 20) combine to form a heavier nucleus, then it is called nuclear fusion.

2. In the nuclear fusion, the mass of the resultant nucleus is less than the sum of the masses of original light nuclei. The mass difference appears as energy. The nuclear fusion never occurs at room temperature unlike nuclear fission. It is because when two light nuclei come closer to combine, it is strongly repelled by the coulomb repulsive force.

3. To overcome this repulsion, the two light nuclei must have enough kinetic energy to move closer to each other such that the nuclear force becomes effective. This can be achieved if the temperature is very much greater than the value 10⁷ K. When the surrounding temperature reaches around 10⁷ K, lighter nuclei start fusing to form heavier nuclei and this resulting reaction is called thermonuclear fusion reaction.

Energy generation in stars:
1. The natural place where nuclear fusion occurs is the core of the stars, since its temperature is of the order of 10⁷ K. In fact, the energy generation in every star is only through thermonuclear fusion. Most of the stars including our Sun fuse hydrogen into helium and some stars even fuse helium into heavier elements.

2. The early stage of a star is in the form of cloud and dust. Due to their own gravitational pull, these clouds fall inward. As a result, its gravitational potential energy is converted to kinetic energy and finally into heat.

3. When the temperature is high enough to initiate the thermonuclear fusion, they start to release enormous energy which tends to stabilize the star and prevents it from further collapse.

4. The sun’s interior temperature is around 1.5 x 10⁷ K. The sun is converting 6 x 10¹¹ kg hydrogen into helium every second and it has enough hydrogen such that these fusion lasts for another 5 billion years.

5. When the hydrogen is burnt out, the sun will enter into new phase called red giant where helium will fuse to become carbon. During this stage, sun will expand greatly in size and all its planets will be engulfed in it.

6. According to Hans Bethe, the sun is powered by proton-proton cycle of fusion reaction. This cycle consists of three steps and the first two steps are as follows:
$_{ 1 }^{ 1 }{ H }$ + $_{ 1 }^{ 1 }{ H }$ → $_{ 1 }^{ 2 }{ H }$ + e⁺ + v …… (1)
$_{ 1 }^{ 1 }{ H }$ + $_{ 1 }^{ 2 }{ H }$ → $_{ 2 }^{ 3 }{ H }$ + γ …… (2)
A number of reactions are possible in the third step. But the dominant one is
$_{ 2 }^{ 3 }{ H }$ + $_{ 12}^{ 3 }{ H }$ → $_{ 2 }^{ 4}{ H }$ + $_{ 1 }^{ 1 }{ H }$ + $_{ 1 }^{ 1 }{ H }$…… (3)
The overall energy production in the above reactions is about 27 MeV. The radiation energy we received from the sun is due to these fusion reactions.

Question 15.
Describe the working of nuclear reactor with a block diagram.
Answer:
Nuclear reactor:
1. Nuclear reactor is a system in which the nuclear fission takes place in a self-sustained controlled manner and the energy produced is used either for research purpose or for power generation.

2. The main parts of a nuclear reactor are fuel, moderator and control rods. In addition to this, there is a cooling system which is connected with power generation set up.

Fuel:
1. The fuel is fissionable material, usually uranium or plutonium. Naturally occurring uranium contains only 0.7% of $_{ 92 }^{ 235 }{ U }$ and 99.3% are only If $_{ 92 }^{ 238 }{ U }$. So the $_{ 92 }^{ 238 }{ U }$ must be enriched such that it contains at least 2 to 4% of $_{ 92 }^{ 235 }{ U }$.

2. In addition to this, a neutron source is required to initiate the chain reaction for the first time. A mixture of beryllium with plutonium or polonium is used as the neutron source. During fission of $_{ 92 }^{ 235 }{ U }$, only fast neutrons are emitted but the probability of initiating fission by it in another nucleus is very low. Therefore, slow neutrons are preferred for sustained nuclear reactions.

Moderators:
1. The moderator is a material used to convert fast neutrons into slow neutrons. Usually the moderators are chosen in such a way that it must be very light nucleus having mass comparable to that of neutrons. Hence, these light nuclei undergo collision with fast neutrons and the speed of the neutron is reduced

2. Most of the reactors use water, heavy water (D₂O) and graphite as moderators. The blocks of uranium stacked together with blocks of graphite (the moderator) to form a large pile.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-21

Control rods:
1. The control rods are used to adjust the reaction rate. During each fission, on an average 2.5 neutrons are emitted and in order to have the controlled chain reactions, only one neutron is allowed to cause another fission and the remaining neutrons are absorbed by the control rods.

2. Usually cadmium or boron acts as control rod material and these rods are inserted into the uranium blocks. Depending on the insertion depth of control rod into the uranium, the average number of neutrons produced per fission is set to be equal to one or greater than one.

3. If the average number of neutrons produced per fission is equal to one, then reactor is said to be in critical state. In fact, all the nuclear reactors are maintained in critical state by suitable adjustment of control rods. If it is greater than one, then reactor is said to be in super-critical and it may explode sooner or may cause massive destruction.

Shielding:
1. For a protection against harmful radiations, the nuclear reactor is surrounded by a concrete wall of thickness of about 2 to 2.5 m.
Cooling system:

2. The cooling system removes the heat generated in the reactor core. Ordinary water, heavy water and liquid sodium are used as coolant since they have very high specific heat capacity and have large boiling point under high pressure.

3. This coolant passes through the fuel block and carries away the heat to the steam generator through heat exchanger. The steam runs the turbines which produces electricity in power reactors.

Question 16.
Explain in detail the four fundamental forces.
Answer:
Fundamental forces of nature:

It is known that there exists gravitational force between two masses and it is universal in nature. Our planets are bound to the sun through gravitational force of the sun.
The force between two charges there exists electromagnetic force and it plays major role in most of our day-today events.
The force between two nucleons, there exists a strong nuclear force and this force is responsible for stability of the nucleus.
In addition to these three forces, there exists another fundamental force of nature called the weak force. This weak force is even shorter in range than nuclear force. This force plays an important role in beta decay and energy production of stars.
During the fusion of hydrogen into helium in sun, neutrinos and enormous radiations are produced through weak force.
Gravitational, electromagnetic, strong and weak forces are called fundamental forces of nature.

Question 17.
Briefly explain the elementary particles of nature.
Answer:
Elementary particles:
1. An atom has a nucleus surrounded by electrons and nuclei is made up of protons and neutrons. Till 1960s, it was thought that protons, neutrons and electrons are fundamental building blocks of matter.

2. In 1964, physicist Murray Gellman and George Zweig theoretically proposed that protons and neutrons are not fundamental particles; in fact they are made up of quarks. These quarks are now considered elementary particles of nature. Electrons are fundamental or elementary particles because they are not made up of anything.
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-22
In the year 1968, the quarks were discovered experimentally by Stanford Linear Accelerator Center (SLAC), USA. There are six quarks namely, up, down, charm, strange, top and bottom and their antiparticles. All these quarks have fractional charges.
For example, charge of up quark is +$\frac { 2 }{ 3 }$e and that of down quark is –$\frac { 1 }{ 3 }$e.

3. According to quark model, proton is made up of two up quarks and one down quark and neutron is made up of one up quark and two down quarks.

4. The study of elementary particles is called particle physics.

Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Exercises

Question 1.
Consider two hydrogen atoms H_A and H_B in ground state. Assume that hydrogen atom H_A is at rest and hydrogen atom H_B is moving with a speed and make head-on collide on the stationary hydrogen atom H_A. After the strike, both of them move together. What is minimum value of the kinetic energy of the moving hydrogen atom H_B, such that any one of the hydrogen atoms reaches one of the excitation state.
Solution:
Collision between hydrogen H_A and hydrogen H_B atom will be inelastic if a part of kinetic energy is used to excite atom.
If u₁ and u₂ are speed of H_A and H_B atom after collision, then
mu = mu₁ + mu₂ …… (1)
$\frac { 1 }{ 2 }$ mu² = $\frac { 1 }{ 2 }$ ${ mu }_{ 1 }^{ 2 }$ + $\frac { 1 }{ 2 }$ ${ mu }_{ 2 }^{ 2 }$ + ∆ E …… (2)
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-23
The minimum K.E of the moving hydrogen atom H_B is 20.4 eV.

Question 2.
In the Bohr atom model, the frequency of transitions is given by the following expression υ = R_c $\left(\frac{1}{n^{2}}-\frac{1}{m^{2}}\right)$, Where n < m,
Consider the following transitions:
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-24
Show that the frequency of these transitions obey sum rule (which is known as Ritz combination principle)
Solution:
In the Bohr atom model, the frequency of transition

IIIrd transition, m = 3 and n = 1

According to Ritz combination principle, the frequency transition of single step is the sum of frequency transition in two steps
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-27

Question 3.
(a) A hydrogen atom is excited by radiation of wavelength 97.5 nm. Find the principal quantum number of the excited state.
(b) Show that the total number of lines in emission spectrum is $\frac { n(n-1) }{ 2 }$ and compute the total number of possible lines in emission spectrum.
Solution:
(a) Wavelength, λ = 97.5 nm = 97.5 x 10^-9 m
Principle quantum number n = ?
According to Bohr atom model,
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-28

(b) A hydrogen atom initially in the ground level absorbs a photon, which excites it to the n = 4 level
So total number of lines in emission spectrum is $\frac { n(n-1) }{ 2 }$
= $\frac { (4(4-1) }{ 2 }$ = $\frac { 4×3) }{ 2 }$ = 6
So the total number of possible lines in emission spectrum is 6.

Question 4.
Calculate the radius of the earth if the density of the earth is equal to the density of the nucleus. [mass of earth 5.97 x 10²⁴ kg].
Solution:
The density of the nucleus of an atom
ρ_N = 2.3 x 10¹⁷ kg m^-3
ρ_N = ρ_E = 2.3 x 10¹⁷ kg m^-3
Mass of the earth M_E = 5.97 x 10²⁴ kg
Density of the earth,
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-29
r³ = 0.62155 x 10⁷ m³
r³ = 183.85 m
r ≈ 180 m.

Question 5.
Calculate the mass defect and the binding energy per nucleon of the $_{ 47 }^{ 108 }{ Ag }$ nucleus, [atomic mass of Ag = 107.905949]
Solution:
Mass of proton, m_p = 1.007825 amu
Mass of neutron, m_n = 1.008665 amu
Mass defect, ∆_m = Zm_p + Z m_N – M_N
= 47 x 1.007825 + 61 x 1.008665 – 107.905949
= 108.89634- 107.905949
∆m = 0.990391 u
Binding energy per nucleon of the $_{ 47 }^{ 108 }{ Ag }$ nucleus
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-30

Question 6.
Half lives of two radioactive elements A and B are 20 minutes and 40 minutes respectively. Initially, the samples have equal number of nuclei. Calculate the ratio of decayed numbers of A and B nuclei after 80 minutes.
Solution:
80 minutes = 4 half lives of A = 2 half live of B
Let the initial number of nuclei in each sample be N.
N_N after 80 minutes = $\frac { N }{{ 2 }^{ 4 }}$
Number of A nuclides decayed = $\frac { 15 }{16}$N
N_B after 80 minutes = $\frac { N }{{ 2 }^{ 4 }}$
Number of B nuclides decayed = $\frac { 3 }{4}$N
Required ratio = $\frac { 15 }{16}$ x $\frac { 4 }{3}$ = $\frac { 5 }{4}$
N_N : N_B = 5 : 4.

Question 7.
On your birthday, you measure the activity of the sample ²¹⁰Bi which has a half-life of 5.01 days. The initial activity that you measure is lμCi . (a) What is the approximate activity of the sample on your next birthday? Calculate (b) the decay constant (c) the mean life (d) initial number of atoms.
Solution:
(a) A year of 365 days is equivalent to 365 d/5.01 d ≈ 73 half-lives. Thus, the activity will be reduced after one year to approximately (1/2)⁷³ (1.000 μCi) ~ 10^-22 μCi.

(b) Initial measure R₀ = 1.000 μCi
= 10^-6 x 3.7 x 10¹⁰
= 3.7 x 10⁴ Bq
After 1 year, the measure R = 10^-22 μCi.
= 10^-22 x 10^-6 x 3.7 x 10¹⁰
= 3.7 x 10^-18 Bq
decay constant,
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-31

(d) Initial number of atoms
R₀ = λN ; N = $\frac {{ R }_{ 0 }}{ λ }$
= $\frac{3.7 \times 10^{4}}{1.6 \times 10^{-6}}$ ; N = 2.31 x 10¹⁰

Question 8.
Calculate the time required for 60% of a sample of radon undergo decay. Given T_1/2 of radon = 3.8 days.
Solution:
Here consider R_n – 222 with a half life of 3.823 days.
From decay equation,
Current amount = Initial amount x (2)^-n
N = N₀ (2)^-n
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-33

Question 9.
Assuming that energy released by the fission of a single $_{ 92 }^{ 235 }{ U }$ nucleus is 200MeV, calculate the number of fissions per second required to produce 1 watt power.
Solution:
The fission of a single $_{ 92 }^{ 235 }{ U }$ nucleus releases 200 MeV of energy
Energy released in the fission is given by the formula,
E = $\frac { Pt }{ n }$ ⇒ $\frac { n }{ t }$ = $\frac { P }{ E }$
E = 200 MeV = 200 x 10⁶ x 1.6 x 10^-19
E = 3.2 x 10^-11 J
$\frac { n }{ t }$ = $\frac { P }{ E }$ = $\frac{1}{3.2 \times 10^{-11}}$ = 0.3125 x 10¹¹ = 3.125 x 10¹⁰$\frac { n }{ t }$ = 3.125 x 10¹⁰

Question 10.
Show that the mass of radium ($_{ 88 }^{ 226 }{ Ra }$) with an activity of 1 curie is almost a gram. Given T1/2 = 1600 years.
Solution:
The activity of the sample at any time t
R = λN
Here, λ = $\frac{0.6931}{\mathrm{T}_{1 / 2}}$
R = 1 Ci = 3.7 x 10¹⁰ dis s^-1T_1/2 = 1600 year = 1600 x 3.16 x 10⁷ dis
∴ The amount of radium,
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-34
= 26990.62 x 10¹⁷
N = 2.7 x 10²¹ atoms
As 226 g of radium contains 6.023 x 10²³ atoms so the amount of required strength.
= $\frac{226 \times 2.7 \times 10^{21}}{6.023 \times 10^{23}}$
= 101.311 x 10^-2
= 1.013 g ≈ 1 g.

Question 11.
Characol pieces of tree is found from an archeological site. The carbon-14 content of this characol is only 17.5% that of equivalent sample of carbon from a living tree. What is the age of tree?
Solution:
R₀ = 100%
R = 17.5%
λ = $\frac{0.6931}{\mathrm{T}_{1 / 2}}$
T_1/2 = 5730 years
According to radioactive law
R = R₀ e^-λt
e^-λt = $\frac {{ R }_{ 0 }}{ R }$
Talking log on both sides
t = $\frac {1}{ λ }$ in $\left( \frac { { R }_{ 0 } }{ R } \right) $
Half life of carbon, T_1/2 = 5730 years
t = $\frac{\mathrm{T}_{1 / 2}}{0.6931}$ In $\left(\frac{1}{0.175}\right)$
= $\frac { 5730 years }{ 0.6931 }$ x 1.74297
= 14409.49 years
t = 1.44 x 10⁴ years.

Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Additional Questions

Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Multiple Choice Questions

Question 1.
The potential difference applied to an X-ray tube is 5 kV and the current through it is 3.2 mA. Then the number of electrons striking the target per second is
(a) 2 x 10¹⁶
(b) 5 x 10¹⁸
(c) 1 x 10¹⁷
(d) 4 x 10⁵
Answer:
(a) 2 x 10¹⁶
Hint:
n = $\frac { It }{ e }$ = $\frac{3.2 \times 10^{-3} \times 1}{1.6 \times 10^{-19}}$ = 2 x 10¹⁶.

Question 2.
The allowed energy for the particle for a particular value of n is proportional to
(a) a^-2
(b) a^-3/2
(c) a^-1
(d) a²
Answer:
(a) a^-2
Hint:
For the standing wave, a = n $\frac { λ }{ 2 }$ or λ= $\frac { 2a }{ n }$
P = $\frac {h}{ λ }$ = $\frac { nh }{ 2a }$ ; E = $\frac {{ p }^{2}}{ 2m}$ = $\frac{n^{2} h^{2}}{2 a^{2} m}$ ; E ∝ a^-2.

Question 3.
A diatomic molecular has moment of inertia I. By Bohr’s quantization condition its rotational energy in the n^th level (n = 0 is not allowed) is
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-35
Answer:

Hint:
Angular momentum, L = $\frac { nh }{ 2π }$
Rotation K.E = $\frac {{ L }^{2}}{ 2I}$ = $\frac{n^{2} h^{2}}{8 \pi^{2} I}$.

Question 4.
The speed of the particle, that can take discrete values is proportional to
(a) n^-3/2
(b) n^-1
(c) n^1/2
(d) n
Answer:
(d) n
Hint:
P = mv = $\frac { nh }{ 2a }$ ; V ∝ n.

Question 5.
If 13.6 eV energy is required to 10 is the hydrogen atom, then energy required to remove an electron from n = 2 is
(a) 10.2 eV
(b) 0 eV
(c) 3.4 eV
(d) 6.8 eV
Answer:
(c) 3.4 eV
Hint:
E_n = $\frac { 13.6 }{ n }^{2}$eV
∴ ∆E = E_∝ – E₂ = 0 + $\frac { 13.6 }{ n }^{2}$ = 3.4 eV.

Question 6.
Which of the following transitions in hydrogen atoms emits photon of highest frequency?
(a) n = 1 to n = 2
(b) n = 2 to n = 6
(c) n = 6 to n = 2
(d) n = 2 to n = 1
Answer:
(d) n = 2 to n = 1
Hint:
The energy difference E₂ – E₁ is maximum as calculated in the above problem.

Question 7.
The wavelengths involved in the spectrum of deuterium $_{ 1 }^{ 2 }{ H }$ are slightly different from that of hydrogen spectrum because
(a) sizes of the two nuclei are different
(b) masses of the two nuclei are different
(c) attraction between the electron and the nucleus is different in the two cases
(d) nuclear forces are different in the two cases
Answer:
(b) masses of the two nuclei are different
Hint:
It is because the masses of the two nuclei are different.

Question 8.
Energy required for the electron excitation in Li⁺⁺ from the first to the third Bohr orbit is
(a) 12.1 eV
(b) 36.3 eV
(b) 36.3 eV
(c) 108.8 eV
Answer:
(c) 108.8 eV
Hint:
E_n = – 13.6 $\frac { { Z }^{ 2 } }{ { n }^{ 2 } } $
∆E = E₃ – E₂ = 13.6 (3)² $\left[ \frac { 1 }{ { 1 }^{ 2 } } -\frac { 1 }{ { 3 }^{ 2 } } \right] $
= $\frac { 13.6×9×8 }{ 9 } $ = 108.8 eV.

Question 9.
Minimum energy required to take out the only one electron from ground state of He⁺ is
(a) 13.6 eV
(b) 54.4 eV
(c) 27.2 eV
(d) 6.8 eV
Answer:
(b) 54.4 eV
Hint:
Ionisation energy, E = 13.6 Z² eV
Fe He⁺, Z = 2
∴ E= 13.6 x (2)² = 13.6 x 4 = 54.4 eV.

Question 10.
Energy of characteristic X-ray is a consequence of
(a) energy of projectile electron
(b) thermal energy of target
(c) transition in target atoms
(d) none of the above
Answer:
(c) transition in target atoms.

Question 11.
How much energy is needed to excite an electron in H-atom from ground state to first excited state?
(a) – 13.6 eV
(b) – 10.2 eV
(c) + 10.2 eV
(d) + 13.6 eV
Answer:
(c) + 10.2 eV
Hint:
E₁ = – 13.6 eV,
E₂ = – 13.6/22² = – 3.4 eV
Required excitation energy
= E₂ – E₂ = – 3.4 + 13.6 = + 10.2 eV.

Question 12.
For an electron in the second orbit of hydrogen, what is the moment of momentum as per the Bohr’s model?
(a) 2πh
(b) πh
(c) h / π
(d) 2h / π
Answer:
(c) h / π
Hint:
In second orbit of hydrogen, L = 2 $\left( \frac { h }{ 2\pi } \right) $ = $\frac { h }{ π }$.

Question 13.
The total energy of an electron in the first excited state of hydrogen atom is about -3.4 eV. Its kinetic energy in this state is
(a) 3.4 eV
(b) 6.8 eV
(c) – 3.4 eV
(d) – 6.8 eV
Answer:
(a) 3.4 eV
Hint:
K.E = – Total energy = +3.4 eV.

Question 14.
The energy of the ground electronic state of hydrogen atom is 13.6 eV. The energy of the first excited state will be
(a) – 27.2 eV
(b) – 52.4 eV
(c) – 3.4 eV
(d) – 6.8 eV
Answer:
(c) – 3.4 eV
Hint:
For the first excited state, n = 2
∴ E₂ = $\frac {{ E }_{ 1 }}{{ E }_{ 2 }}$ = $\frac {-13.6 eV}{4}$ = -3.4 eV.

Question 15.
The total energy of electron in the ground state of hydrogen atom is – 13.6 eV. The kinetic energy of an electron in the first excited state is
(a) 6.8 eV
(b) 13.6 eV
(c) 1.7 eV
(d) 3.4 eV
Answer:
(d) 3.4 eV
Hint:
Total energy in the first excited state,
E₂ = $\frac {{ E }_{ 1 }}{{ E }_{ 2 }}$ = $\frac {{ E }_{ 1 }}{{ 2 }^{ 2 }}$ = $\frac {-13.6 }{4}$ = -3.4 eV
K.E = -E₂ = 3.4 eV.

Question 16.
Bohr’s theory of hydrogen atom did not explain fully
(a) diameter of H-atom
(b) emission spectra
(c) ionisation energy
(d) the fine structure of even hydrogen spectrum
Answer:
(d) the fine structure of even hydrogen spectrum
Hint:
Bohr theory could not explain the five structure of hydrogen spectrum.

Question 17.
In Bohr’s model of an atom, which of the following is an integral multiple of $\frac { h }{ 2\pi } $ ?
(a) Kinetic energy
(b) Radius of an atom
(c) Potential energy
(d) Angular momentum
Answer:
(d) Angular momentum
Hint:
L = mvr = $\frac { nh }{ 2\pi } $.

Question 18.
According to Bohr’s theory, relation between n and radius of orbit is:
(a) r ∝ $\frac { 1 }{ n } $
(b) r ∝ n
(c) r ∝ n²
(d) r ∝ $\frac { 1 }{{ n }^{2}} $
Answer:
(c) r ∝ n²
Hint:
r = $\frac{n^{2} h^{2}}{4 \pi^{2} m K Z e^{2}}$ i.e., r ∝ n².

Question 19.
In Bohr’s model of hydrogen atom, the radius of the first electron orbit is 0.53 Å. What will be the radius of the third orbit?
(a) 4.77 Å
(b) 47.7 Å
(c) 9 Å
(d) 0.09 Å
Answer:
(a) 4.77 Å
Hint:
r₃ = (3)²r¹= 9 x 0.53 = 4.77 Å.

Question 20.
In Bohr model of hydrogen atom, which of the following is quantised?
(a) linear velocity of electron
(b) angular velocity of electron
(c) linear momentum of electron
(d) angular momentum of electron
Answer:
(d) angular momentum of electron.

Question 21.
In Bohr’s model, the atomic radius of the first orbit is r₀. Then, the radius of the third orbit is
(a) r₀/9
(b) r₀
(c) 9r₀
(d) 3r₀
Answer:
(c) 9r₀
Hint:
r_n = r₁ n², where r₁ = r₀
∴ v₃ = r₀ (3)² 9r₀

Question 22.
What is ratio of Bohr magneton to the nuclear magneton?
(a) $\frac {{ m }_{ p }}{{ m }_{ e }}$
(b) $\frac{m_{p}^{2}}{m_{e}^{2}}$
(c) 1
(d) $\frac {{ m }_{ e }}{{ m }_{ p }}$
Answer:
(a) $\frac {{ m }_{ p }}{{ m }_{ e }}$
Hint:
Bohr magneton, μ_B = $\frac {eh}{{ 2m }_{ e }}$
Nuclear magneton, μ_N = $\frac {eh}{{ 2m }_{ p }}$
∴ $\frac {{ μ }_{ B }}{{ μ }_{ N }}$ = $\frac {{ m }_{ p }}{{ m }_{ e }}$.

Question 23.
In terms of Bohr radius a₀, the radius of the second Bohr orbit of a hydrogen atom is given by
(a) 4a₀
(b) 8a₀
(c) √2a₀
(d) 2a₀
Answer:
(a) 4a₀
Hint:
r_n = r₁ n²
r₂ = a₀ (2)² =4a₀

Question 24.
If an a-particle collides head on with a nucleus, what is impact parameter?
(a) zero
(b) infinite
(c) 10^-10 m
(d) 10¹⁰ m
Answer:
(a) zero

Question 25.
One femtometre is equivalent to
(a) 10¹⁵ m
(b) 10^-15 m
(c) 10^-12 m
(d) 10¹¹ m
Answer:
(b) 10^-15 m

Question 26.
Wavelength of K_α line of X-ray spectra varies with atomic number as
(a) λ ∝ Z
(b) λ ∝ √Z
(c) λ ∝ $\frac { 1 }{{ Z }^{2}}$
(d) λ ∝ $\frac { 1 }{ √Z }$
Answer:
(c) λ ∝ $\frac { 1 }{{ Z }^{2}}$
Hint:
ccording to moseley’s law, √V = a(Z – b) or V = $\frac { c }{ λ }$ = a² (Z – b)²
∴ (c) λ ∝ $\frac { 1 }{{ Z }^{2}}$.

Question 27.
The shortest wavelength of X-rays, emitted from a X-ray tube, depend upon
(a) current in the tube
(b) voltage applied to the tube
(c) nature of glass material in the tube
(d) atomic number of the target material
Answer:
(b) voltage applied to the tube
Hint:
λ_min = $\frac { 12375 }{V (volt)}$ Å ; λ_min ∝ $\frac { 1 }{ V }$.

Question 28.
During X-ray formation, if voltage is increased
(a) minimum wavelength decreases
(b) minimum wavelength increases
(c) intensity decreases
(d) intensity increases
Answer:
(a) minimum wavelength decreases
Hint:
As λ_min ∝ $\frac { 1 }{ V }$ if voltage is increased, the minimum wavelength of X-rays emitted decreases.

Question 29.
What would be the radius of second orbit of He⁺ ions?
(a) 1.058 Å
(b) 3.023 Å
(c) 2.068 Å
(d) 4.458 Å
Answer:
1.058 Å
Hint:
r_n = $\frac {{ n }^{2}}{ Z }$ r₁
For He⁺ ion, n = 2, Z = 2
∴ r₂ = $\frac {4}{ 2 }$ x 0.59 Å = 1.058 Å.

Question 30.
The minimum wavelength of the X-rays produced by electrons accelerated through a potential difference of V volts is directly proportional to
(a) $\frac { 1 }{ √V }$
(b) $\frac { 1 }{ V }$
(c) √V
(d) V²
Answer:
(b) $\frac { 1 }{ V }$
Hint:
$\frac { hc }{ λ }$ =eV or λ = $\frac { hc }{ eV }$, i.e., λ ∝ $\frac { 1 }{ V }$.

Question 31.
Which source is associated with a line emission spectrum?
(a) Electric fire
(b) Neon street sign
(c) Red traffic light
(d) Sun
Answer:
(b) Neon street sign

Question 32.
Which one of the relation is correct between time period and number of orbits while an electron is revolving in a orbit?
(a) T ∝ $\frac { 1 }{{ n }^{2}}$
(b) T ∝ n²
(c) T ∝ n³
(d) T ∝ $\frac { 1 }{{ n }^{2}}$
Answer:
(c) T ∝ n³
Hint:
In Bohr’s atomic model, T ∝ n³.

Question 33.
The size of atom is proportional to
(a) A
(b) A^1/3
(c) A^2/3
(d) A^-1/3
Answer:
(b) A^1/3

Question 34.
If an electron jumps from 1st orbit to 3rd orbit, then it will
(a) not lose energy
(b) not given energy
(c) release energy
(d) absorb energy
Answer:
(d) absorb energy
Hint:
Only by absorbing energy, an electron jumps from first orbit to third orbit.

Question 35.
According to uncertainty principle for an electron, time measurement will become uncertain if following is measured with high certainty
(a) energy
(b) momentum
(c) location
(d) velocity
Answer:
(a) energy
Hint:
According to uncertainty principle, ∆E.∆t ≥ $\frac { h }{ 2π }$.

Question 36.
According to Rutherford’s atomic model, the electrons inside an atom are
(a) stationary
(b) centralized
(c) non-stationary
(d) none of these
Answer:
(c) non-stationary
Hint:
According to Rutherford model, the electron inside an atom cannot be stationary.

Question 37.
Wavelength of a light emitted from second orbit to first orbit in a hydrogen atom is
(a) 1.215 x 10^-7 m
(b) 1.215 x 10^-5 m
(c) 1.215 x 10^-4 m
(d) 1.215 x 10^-3 m
Answer:
(a) 1.215 x 10^-7 m
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-37

Question 38.
In terms of Rydberg constant R, the wave number of the first Balmer line is
(a) R
(b) 3R
(c) $\frac { 5R }{ 36 }$
(d) $\frac { 8R }{ 9 }$
Answer:
(c) $\frac { 5R }{ 36 }$
Hint:
For the first Balmer line, $\bar { v } $ =$\frac { 1 }{ λ }$ = R$\left(\frac{1}{2^{2}}-\frac{1}{3^{2}}\right)$ =$\frac { 5R }{ 36 }$.

Question 39.
The K_∝ X-ray emission line of tungsten occurs at λ = 0.021 nm. The energy difference between K and L levels in this atom is about
(a) 0.51 MeV
(b)1.2MeV
(c) 59 keV
(d) 136
Answer:
(c) 59 keV
Hint:
E = $\frac { hc }{ λ }$ = $\frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{0.021 \times 10^{-9}}$ eV = 589.3 x 10² eV ≈ 59 KeV.

Question 40.
The radius of an electron orbit in a hydrogen atom is of the order of
(a) 10^-8 m
(b) 10^-9 m
(c) 10^-11 m
(d) 10^-13 m
Answer:
(c) 10^-11 m

Question 41.
Which of the following atoms has the lowest ionisation potential?
(a) $_{ 7 }^{ 14 }{ N }$
(b) $_{ 55 }^{ 133 }{ Cs }$
(c) $_{ 18 }^{ 40 }{ Ar }$
(d) $_{ 8 }^{ 16 }{ O }$
Answer:
(b) $_{ 55 }^{ 133 }{ Cs }$
Hint:
In $_{ 55 }^{ 133 }{ Cs }$, the outermost electron is farthest from the nucleus and so minimum energy is required to remove this electron from the atom. Hence $_{ 55 }^{ 133 }{ Cs }$ has lowest concision potential.

Question 42.
The transition from the state n = 4 to n = 3 in a hydrogen like atom result in ultraviolet radiation. Infrared radiation will be obtained in the transition from
(a) 2 → 1
(b) 3 → 2
(c) 4 → 2
(d) 5 → 4
Answer:
(d) 5 → 4
Hint:
The energy gap between 4^th and 3^rd states is more than the gap between 5^th and 4^th states.

Question 43.
The number of waves, contained in unit length of the medium, is called
(a) elastic wave
(b) wave number
(c) wave pulse
(d) electromagnetic wave
Answer:
(b) wave number
Hint:
The number of waves contained in a unit length of the medium is called a wave number.

Question 44.
When hydrogen atom is in its first excited level, its radius is
(a) sarhe
(b) half
(c) twice
(d) four times
Answer:
(d) four times
Hint:
r₂ = r₁ (2)² = 4r₁

Question 45.
The ground state energy of hydrogen atom is -13.6 eV. What is the potential energy of the electron in this state?
(a) 0 eV
(b) -27.2 eV
(c) 1 eV
(d) 2 eV
Answer:
(b) -27.2 eV
Hint:
PE = 2 x Total energy = 2 x (-13.6) = – 27.2 eV.

Question 46.
For ionising an excited hydrogen atom, the energy required (in eV) will be
(a) a little less than 13.6
(b) 13.6
(c) more than 13.6 eV
(d) 3.4 or less
Answer:
(d) 3.4 or less
Hint:
The energy of the electron is – 3.4 eV in first excited state and the its magnitude is less for higher excited state.

Question 47.
What is the energy of He⁺ electron in first order?
(a) 40.8 eV
(b) -27.2 eV
(c) -54.4 eV
(d)-13.6eV
Answer:
(c) -54.4 eV
Hint:
For hydrogen like atoms or ions, E_n = $\frac{-13.6 Z^{2}}{n^{2}}$ eV
For He⁺, Z = 2 and n = 1
E₁ = $\frac{-13.6 \times 2^{2}}{12}$ 54.4 eV.

Question 48.
If voltage across on X-ray tube is doubled, then energy of X-ray emitted by
(a) be doubled
(b) be quadrupled
(c) become half
(d) remain the same
Answer:
(d) remain the same
Hint:
The energy of the X-rays depends on the nature of the target material. Thus the energy of the X-rays remain the same.

Question 49.
When hydrogen atom is in its first excited level, its radius is of the Bohr radius.
(a) twice
(b) 4 times
(c) same
(d) half
Answer:
(b) 4 times
Hint:
For first excited level, n = 2
r₂ = (2)² r₀ = 4r₀

Question 50.
The ionisation energy of hydrogen atom is 13.6 eV, the ionisation energy of a singly ionsed helium atom would be
(a) 13.6 eV
(b) 27.2 eV
(c) 6.8 eV
(d) 54.4 eV
Answer:
(d) 54.4 eV
Hint:
${ E }_{ 2 }^{ 1 }$ = (2)² E₁ = 4 x 13.6 = 54.4 eV.

Question 51.
When an electron makes transition from n = 4 to n = 2, then emitted line spectrum will be
(a) first line of lyman series
(b) second line of Balmer series
(c) first line of paschen series
(d) second line of paschen series
Answer:
(b) second line of Balmer series
Hint:
The transition from n = 4 to n = 2 emits second line of Balmer series.

Question 52.
Maximum frequency of emission is obtained for the transition
(a) n = 2 to n = 1
(b) n = 6 to n = 2
(c) n = 1 to n = 2
(d) n = 2 to n = 6
Answer:
(a) n = 2 to n = 1
Hint:
The energy difference E₂ – E₁ is maximum, so photon of maximum frequency is emitted in transition n = 2 to n = 1.

Question 53.
Hydrogen atoms are excited from ground state to the state of principle quantum number 4. Then the number of spectral lines observed will be
(a) 3
(b) 6
(c) 5
(d) 2
Answer:
(b) 6
Hint:
Here n = 4
∴ The number of spectral lines emitted $\frac { n(n-1) }{ 2 }$ = $\frac { 4×3 }{ 2 }$ = 6

Question 54.
The radius of hydrogen atom, in the ground state is of the order of
(a) 10^-18 cm
(b) 10^-7 cm
(c) 10^-6 cm
(d) 10^-4 cm
Answer:
(a) 10^-18 cm
Hint:
Radius of first orbit of H-atom = 0.53 Å ≈ 10^-8 cm.

Question 56.
According to Bohr’s theory of the hydrogen atom, the speed v_n of the electron in a stationary orbit is related to the principal quantum number n as (c is a constant)
(a) v_n = c/n²
(b) v_n = c/n
(c) v_n = c x n
(d) v_n = c x n²
Answer:
(b) v_n = c/n
Hint:
Speed of electron in n^th orbit, υ_n= c/n.

Question 57.
Out of the following which one is not possible energy for a photon to be emitted by hydrogen atom according to Bohr’s atomic model?
(a) 13.6 eV
(b) 0.65 eV
(c) 1.9 eV
(d) 11.1 eV
Answer:
(d) 11.1 eV
Hint:
For no two energy levels of hydrogen atom, E₂ – E₁ = 11.1 eV.

Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Short Answer Questions

Question 1.
Write down the drawbacks of Rutherford model.
Answer:
1. Drawbacks of Rutherford model:
Rutherford atom model helps in the calculation of the diameter of the nucleus and also the

2. Size of the atom but has the following limitations:
(a) This model fails to explain the distribution of electrons around the nucleus and also the stability of the atom. According to classical electrodynamics, any accelerated charge emits electromagnetic radiations. Due to emission of radiations, it loses its energy.

Hence, it can no longer sustain the circular motion. The radius of the orbit, therefore, becomes smaller and smaller (undergoes spiral motion) and finally the electron should fall into the nucleus and the atoms should disintegrate. But this does not happen. Hence, Rutherford model could not account for the stability of atoms.

(b) According to this model, emission of radiation must be continuous and must give continuous emission spectrum but experimentally we observe only line (discrete) emission spectrum for atoms.

Question 2.
Define excitation potential.
Answer:
Excitation potential is defined as excitation energy per unit charge.

Question 3.
What is meant by atomic number?
Answer:
The number of protons in the nucleus is called the atomic number and it is denoted by Z.

Question 4.
What is meant by neutron number?
Answer:
The number of neutrons in the nucleus is called neutron number (N).

Question 5.
What is meant by mass number?
Answer:
The total number of neutrons and protons in the nucleus is called the mass number and it is denoted by A. Hence, A = Z + N.

Question 6.
Write down the properties of neutrino.
Answer:
The neutrino has the following properties:

It has zero charge
It has an antiparticle called anti-neutrino.
Recent experiments showed that the neutrino has very tiny mass.
It interacts very weakly with the matter. Therefore, it is very difficult to detect. In fact, in every second, trillions of neutrinos coming from the sun are passing through our body without any interaction.

Samacheer Kalvi 12th Physics Atomic and Nuclear Physics Numerical Problems

Question 1.
What is the distance of closest approach when a 5 MeV proton approaches a gold nucleus.
Solution:
q₁ = ze
q₂ = e
At the distance r₀of closest approach,
K.E of a Proton = P.E. of proton and the gold nucleus
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-38

Question 2.
Calculate the impact parameter of a 5 MeV particle scattered by 90° when it approaches.
Solution:
KE = 5 MeV = 5 x 10⁶ x 1.6 x 10^-19 J
θ = 90°
For gold, Z = 79
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-39

Question 3.
What is the angular momentum of an electron in the third orbit of an atom?
Solution:
Here n = 3; h = 6.6 x 10^-34 Js
Angular momentum,
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-40

Question 4.
Write down the expression for the radii of orbits of hydrogen atom. Calculate the radius of the smallest orbit.
Solution:
The radius of the n^th orbit of a hydrogen atom is given by
r = $\frac{n^{2} h^{2}}{4 \pi^{2} m K e^{2}}$
Radius of innermost orbit, called Bohr’s radius, is obtained by putting n = 1. It is denoted by r₀
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-41
r₀ = 0.53 x 10^-10 m = 0.53 A°.

Question 5.
Calculate the frequency of the photon, which can excite the electron to – 3.4 eV from -13.6 eV.
Solution:
Energy of photon, hυ = E₂ – E₁
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-42
υ = 2.47 x 10¹⁵ Hz

Question 6.
The ground state energy of hydrogen atom is -13.6 eV. If an electron makes a transition from an energy level -0.85 eV to -1.51 eV, Calculate the wavelenth of the spectral line emitted. To which series of hydrogen spectrum does this wavelenth belong?
Solution:
Here ∆E = E₂ – E₁ = -0.85-(-1.51).
= 0.66 eV
∆E = 0.66 x 1.6 x 10^-19 J
λ = $\frac { hc }{ ∆E }$ = $\frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{0.66 \times 1.6 \times 10^{-19}}$
= 18.84 x 10^-7
λ = 18840 Å
This wavelength belongs to the Pachen series of the hydrogen spectrum.

Question 7.
Express 16 rag mass into equivalant energy in eV.
Solution:
Here m = 16 mg = 16 x 10^-16 kg, C = 3 x 10⁸ ms^-1
Equivalent energy, E = mc²
= 16 x 10^-16 x (3 x 10⁸)² J
= $\frac{16 \times 10^{-6} \times\left(3 \times 10^{8}\right)^{2}}{1.6 \times 10^{-19}} \mathrm{eV}$
E = 9 x 10³⁰ eV.

Question 8.
The nuclear mass of $_{ 26 }^{ 56 }{ Fe }$ is 55.85 amu. Calculate its nuclear density.
Solution:
Here M_Fe = 55.85 amu = 55.85 x 1.66 x 10^-27 kg
= 9.27 x 10^-26 kg
Nuclear Mass = R₀ A^1/3 = 1.1 x 10^-15 x (56)^1/3 m
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-43
ρ_nu = 2.9 x 10¹⁷ kg m^-3.

Question 9.
Calculate the density of hydrogen nuclear in SI units. Given R₀ = 1.1 fermi and m_p = 1.007825 amu.
Solution:
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-44
ρ = 2.98 x 10¹⁷ kg m^-3.

Question 10.
Express one atomic mass unit in energy units, first in Joules and then in MeV. Using this, express the mass defect of $_{ 8 }^{ 16 }{ O }$ in MeV.
Solution:
We have, m = 1 amu = 1.66 x 10^-27 kg, c = 3 x 10⁸ ms^-1
E = mc₂ = 1.66 x 10^-27 x (3 x 10⁸)²
= 14.94 x10^-11 J
= $\frac{1.494 \times 10^{-10}}{1.6 \times 10^{-13}} \mathrm{MeV}$ [ 1 MeV = 1.6 x 10^-13]
= 931.5 MeV
The $_{ 8 }^{ 16 }{ O }$ nucleus contains 8 protons and 8 neutrons
Mass of 8 protons = 8 x 1.00727 = 8. 05816 amu
Mass of 8 neutrons = 8 x 1.00866 = 8. 06928 amu
Total Mass = 16.12744 amu
Mass of $_{ 8 }^{ 16 }{ O }$ nucleus = 15.99053 amu
Mass defect = 0.13691 amu
∆E_b = 0.13691 x 931.5 Mev
∆E_b = 127.5 Mev

Question 11.
The decay constant, for a given redioactive sample is 0.3465 / day. What percentage of this sample will get decayed in a period of 4 years?
Solution:
Here λ, = 0.3465/day; t = 4 years
Samacheer Kalvi 12th Physics Solutions Chapter 8 Atomic and Nuclear Physics-45
Hence sample left undecayed after a period of 4 years,

Question 12.
If 200 MeV energy is released in the fission of a single nucleus of $_{ 92 }^{ 235 }{ U }$, how many fissions must occur to produce a power of 1 kW?
Solution:
Let the number of fissions per second be n.
Then, Energy released per second = n x 200 MeV
= n x 200 x 1.6 x 10^-13 J
Energy required per second = Power x Time
= 1kW x 1 s = 1000 J
Energy released = Energy required
n x 200 x 1.6 x 10^-13 = 1000
n = 3.125 x 10^-13

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Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter

April 15, 2024

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Tamilnadu Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter

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Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Textual Evaluation Solved

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Multiple Choice Questions

Question 1.
The wavelength λ_e of an electron and λ_p of a photon of same energy E are related by …….. .
(a) λ_p ∝ λ_e
(b) λ_p ∝ $\sqrt { { \lambda }_{ e } } $
(c) λ_p ∝ $\frac { 1 }{ \sqrt { { \lambda }_{ e } } } $
(d) λ_p ∝ ${ \lambda }_{ e }^{ 2 }$
Answer:
(d) λ_p ∝ ${ \lambda }_{ e }^{ 2 }$
Hint:
de broglie wavelength of electron, λ_e = $\frac { h }{ \sqrt { 2mE } } $
∴ ie λ_e ∝ $\frac { 1 }{ \sqrt { E } } $ ⇒ ${ \lambda }_{ e }^{ 2 }$ ∝ $\frac { 1 }{ E } $ …… (1)
de-Broglie wavelength of proton
λ_p = $\frac { hc }{ E } $
λ_p ∝ $\frac { 1 }{ E } $ …… (2)
From (1) and (2)
${ \lambda }_{ e }^{ 2 }$ ∝ λ_p i.e., λ_p ∝ ${ \lambda }_{ e }^{ 2 }$

Question 2.
In an electron microscope, the electrons are accelerated by a voltage of 14 kV. If the voltage is changed to 224 kV, then the de Broglie wavelength associated with the electrons would …….. .
(a) increase by 2 times
(b) decrease by 2 times
(c) decrease by 4 times
(d) increase by 4 times
Answer:
(c) decrease by 4 times
Hint:
At Voltage, V = 14 kV
de-Broglie wavelength of electron,
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-1
de-Broglie wavelength of electron is decreased by 4 times

Question 3.
A particle of mass 3 x 10^-6 g has the same wavelength as an electron moving with a velocity
6 x 10⁶ ms^-1 The velocity of the particle is …….. .
(a) 1.82 x 10^-18 ms^-1
(b) 9 x 10^-2 ms^-1
(c) 3 x 10^-31 ms^-1
(d)1.82 x 10^-15 ms^-1
Answer:
(d)1.82 x 10^-15 ms^-1
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-2
Velocity of the particle

Question 4.
When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2λ, the stopping potential is $\frac { V }{ 4 }$. The threshold wavelength for the metallic surface is ………. .
(a) 4λ
(b) 5λ
(c) $\frac { 5 }{ 2 }$ λ
(d) 3λ
Answer:
(d) 3λ
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-4
On solving we get, λ₀ = 3λ

Question 5.
If a light of wavelength 330 nm is incident on a metal with work function 3.55 eV, the electrons are emitted. Then the wavelength of the emitted electron is (Take h = 6.6 x 10^-34 Js) ……… .
(a) < 2.75 x 10^-9 m
(b) ≥ 2.75 x 10^-9 m
(c) < 2.75 x 10^-12um
(d) ≤ 2.75 x 10^-10um
Answer:
(a) < 2.75 x 10^-9 m
Hint:
Maximum KE of emitted electron is
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-5
de-Broglie wavelength of emitted electron

The Two wavelength of the emitted electron is < 2.75 x 10^-9 m

Question 6.
A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and $\frac { λ }{ 2 }$ . If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function at the surface of material is …….. .
(a) $\frac { hc }{ λ }$
(b) $\frac { 2hc }{ λ }$
(c) $\frac { hc }{ 3λ }$
(d) $\frac { hc }{ 2λ }$
Answer:
(d) $\frac { hc }{ 2λ }$
Hint:
KE₁ = $\frac { hc }{ λ }$ – Φ ……. (2)
3KE₁ = $\frac { 2hc }{ λ }$ – Φ
KE₁ = $\frac { 2hc }{ 3λ }$ – $\frac { Φ }{ 3λ}$ ….. (2)
Equating (1) and (2)
$\frac { hc }{ λ }$ – Φ = $\frac { 2hc }{ 3λ }$ – $\frac { Φ }{ 3λ}$
$\frac { hc }{ 3λ }$ = $\frac { 2Φ }{ 3λ}$ ⇒ Φ = $\frac { hc }{ 2λ }$

Question 7.
In photoelectric emission, a radiation whose frequency is 4 times threshold frequency of a certain metal is incident on the metal. Th en the maximum possible velocity of the emitted electron will be ……….. .
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-7
Answer:

Hint:
From Einstein’s photoelectric equation

Question 8.
Two radiations with photon energies 0.9 eV and 3.3 eV respectively are falling on a metallic surface successively. If the work function of the metal is 0.6 eV, then the ratio of maximum speeds of emitted electrons will be ………..
(a) 1 : 4
(b) 1 : 3
(c) 1 : 1
(d) 1 : 9
Answer:
(b) 1 : 3
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-10

Question 9.
A light source of wavelength 520 nm emits 1.04 x 10¹⁵photons per second while the second source of 460 nm produces 1.38 x 10¹⁵ photons per second. Then the ratio of power of second source to that of first source is ……… .
(a) 1.00
(b) 1.02
(c) 1.5
(d) 0.98
Answer:
(c) 1.5
Hint:
Power:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-12

Question 10.
The mean wavelength of light from sun is taken to be 550 nm and its mean power is 3.8 x 10²⁶ W. The number of photons received by the human eye per second on the average from sunlight is of the order of ………. .
(a) 10⁴⁵
(b) 10⁴²
(c) 10⁵⁴
(d) 10⁵¹
Answer:
(a) 10⁴⁵
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-13

Question 11.
The threshold wavelength for a metal surface whose photoelectric work function is 3.313 eV is
(a) 4125 Å
(b) 3750 Å
(c) 6000 Å
(d) 2062.5 Å
Answer:
(b) 3750 Å
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-14

Question 12.
A light of wavelength 500 nm is incident on a sensitive plate of photoelectric work function 1.235 eV. The kinetic energy of the photo electrons emitted is be (Take h = 6.6 x 10^-34 Js)
(a) 0.58 eV
(b) 2.48 eV
(c) 1.24 eV
(d) 1.16 eV
Answer:
(c) 1.24 eV
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-15

Question 13.
Photons of wavelength λ are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular arc of radius R by a perpendicular magnetic field having magnitude B. The work function of the metal is ……… .
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-16
Answer:

Hint:
Magnetic lorentz force = Centripetal force

From Einstein’s photo electric equation

Question 14.
The work functions for metals A, B and C are 1.92 eV, 2.0 eV and 5.0 eV respectively. The metals which will emit photoelectrons for a radiation of wavelength 4100 Å is/are ………. .
(a) A only
(b) both A and B
(c) all these metals
(d) none
Answer:
(b) both A and B
Hint:
Energy of radiation
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-20
E = 3.04 eV
Since energy of incident radiation is greater than the work function of metals A and B. So metal A and B will emit photoelectrons.

Question 15.
Emission of electrons by the absorption of heat energy is called ……… emission.
(a) photoelectric
(b) field
(c) thermionic
(d) secondary
Answer:
(c) thermionic

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Short Answer Questions

Question 1.
Why do metals have a large number of free electrons?
Answer:
In metals, the electrons in the outer most shells are loosely bound to the nucleus. Even at room temperature, there are a large number of free electrons which are moving inside the metal in a random manner.

Question 2.
Define work function of a metal. Give its unit.
Answer:
The minimum energy needed for an electron to escape from the metal surface is called work function of that metal. It’s unit is electron volt (eV).

Question 3.
What is photoelectric effect?
Answer:
The ejection of electrons from a metal plate when illuminated by light or any other electromagnetic radiation of suitable wavelength (or frequency) is called photoelectric effect.

Question 4.
How does photocurrent vary with the intensity of the incident light?
Answer:
Photocurrent – the number of electrons emitted per second is directly proportional to the intensity of the incident light.

Question 5.
Give the definition of intensity of light and its unit.
Answer:
Intensity of light refer to the strength or brightness or amount of light produced by a specific source. It’s unit is candela (cd)

Question 6.
How will you define threshold frequency?
Answer:
For a given surface, the emission of photoelectrons takes place only if the frequency of incident light is greater than a certain minimum frequency called the threshold frequency.

Question 7.
What is a photo cell? Mention the different types of photocells.
Answer:
photocells: Photo electric cell or photo cell is a device which converts light energy into electrical energy. It works on the principle of photo electric effect.
Types:

Photo emissive cell
Photo voltaic cell
Photo conductive cell

Question 8.
Write the expression for the de Broglie wavelength associated with a charged particle of charge q and mass m, when it is accelerated through a potential V.
Answer:
An electron of mass m is accelerated through a potential difference of V volt. The kinetic energy acquired by the electron is given by
$\frac { 1 }{ 2 }$ mv² = eV
Therefore, the speed v of the electron is v = $\sqrt { \frac { 2ev }{ m } } $
Hence, the de Broglie wavelength of the electron is λ = $\frac { h }{ mv }$ = $\frac { h }{ \sqrt { 2emV } } $

Question 9.
State de Broglie hypothesis.
Answer:
De Broglie hypothesis, all matter particles like electrons, protons, neutrons in motion are associated with waves.

Question 10.
Why we do not see the wave properties of a baseball?
Answer:
Due to the large mass of a baseball, the de Broglie wavelength
[λ = $\frac { h }{ mv }$] associated with a moving baseball is very small. Hence its wave nature is not visible.

Question 11.
A proton and an electron have same kinetic energy. Which one has greater de Broglie wavelength. Justify.
Answer:
de-Broglie wavelength of the particle is λ = $\frac { h }{ p }$ = $\frac { h }{ \sqrt { 2mK } } $
i.e. λ ∝ $\frac { h }{ \sqrt { m } } $
As m_e << m_p, so λ_e >> λ_p
Hence protons have greater de-Broglie wavelength.

Question 12.
Write the relationship of de Broglie wavelength λ associated with a particle of mass m in terms of its kinetic energy K.
Answer:
Kinetic energy of the particle, K = $\frac { 1 }{ 2 }$ mv² = $\frac { { P }^{ 2 } }{ 2m } $
p = $\sqrt { 2mK } $
de-Broglie wavelength of the particle λ = $\frac { h }{ p }$ = $\frac { h }{ \sqrt { 2mK } } $

Question 13.
Name an experiment which shows wave nature of the electron. Which phenomenon was observed in this experiment using an electron beam?
Answer:

Davisson – Germer experiment confirmed the wave nature of electrons.
They demonstrated that electron beams are diffracted when they fall on crystalline solids.

Question 14.
An electron and an alpha particle have same kinetic energy. How are the de Broglie wavelengths associated with them related?
Answer:
[λ = $\frac { h }{ p }$]
Kinetic energy of the particle K = $\frac { 1 }{ 2 }$ mv² = $\frac { { P }^{ 2 } }{ 2m } $ = $\frac { { h }^{ 2 } }{ 2m{ \lambda }^{ 2 } } $
i.e. λ = $\frac { h }{ \sqrt { 2mK } } $ ; λ ∝ $\frac { 1 }{ \sqrt { m} } $
$\frac { { \lambda }_{ e } }{ { \lambda }_{ \alpha } } $ = $\sqrt { \frac { { m }_{ \alpha } }{ { m }_{ e } } } $

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Long Answer Questions

Question 1.
What do you mean by electron emission? Explain briefly various methods of electron emission.
Answer:
Electron emission:
1. Free electrons possess some kinetic energy and this energy is different for different electrons. The kinetic energy of the free electrons is not sufficient to overcome the surface barrier.

2. Whenever an additional energy is given to the free electrons, they will have sufficient energy to cross the surface barrier. And they escape from the metallic surface.

3. The liberation of electrons from any surface of a substance is called electron emission.

There are mainly four types of electron emission which are given below.
(i) Thermionic emission:
When a metal is heated to a high temperature, the free electrons on the surface of the metal get sufficient energy in the form of thermal energy so that they are emitted from the metallic surface. This type of emission is known as thermionic emission.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-21
The intensity of the thermionic emission (the number of electrons emitted) depends on the metal used and its temperature.

Examples: cathode ray tubes, electron microscopes, X-ray tubes etc.

(ii) Field emission:
Electric field emission occurs when a very strong electric field is applied across the metal. This strong field pulls the free electrons and helps them to overcome the surface barrier of the metal.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-23
Examples: Field emission scanning electron microscopes, Field-emission display etc.

(iii) Photo electric emission:
When an electromagnetic radiation of suitable frequency is incident on the surface of the metal, the energy is transferred from the radiation to the free electrons. Hence, the free electrons get sufficient energy to cross the surface barrier and the photo electric emission takes place. The number of electrons emitted depends on the intensity of the incident radiation.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-24
Examples: Photo diodes, photo electric cells etc.

(iv) Secondary emission:
When a beam of fast moving electrons strikes the surface of the metal, the kinetic energy of the striking electrons is transferred to the free electrons on the metal surface. Thus the free electrons get sufficient kinetic energy so that the secondary emission of , electron occurs.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-25
Examples: Image intensifies, photo multiplier tubes etc.

Question 2.
Briefly discuss the observations of Hertz, Hallwachs and Lenard.
Answer:
Hertz observation:
1. In 1887, Heinrich Hertz first became successful in generating and detecting electromagnetic wave with his high voltage induction coil to cause a spark discharge between two metallic spheres.

2. When a spark is formed, the charges will oscillate back and forth rapidly and the electromagnetic waves are produced.

3. The electromagnetic waves thus produced were detected by a detector that has a copper wire bent in the shape of a circle. Although the detection of waves is successful, there is a problem in observing the tiny spark produced in the detector.

4. In order to improve the visibility of the spark, Hertz made many attempts and finally noticed an important thing that small detector spark became more vigorous when it was exposed to ultraviolet light.

5. The reason for this behaviour of the spark was not known at that time. Later it was found that it is due to the photoelectric emission.

6. Whenever ultraviolet light is incident on the metallic sphere, the electrons on the outer surface are emitted which caused the spark to be more vigorous.

Hallwachs’ observation:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-26

8. In 1888, Wilhelm Hallwachs, a German physicist, confirmed that the strange behaviour of the spark is due to the action of ultraviolet light with his simple experiment.

9. A clean circular plate of zinc is mounted on an insulating stand and is attached to a gold leaf electroscope by a wire. When the uncharged zinc plate is irradiated by ultraviolet light from an arc lamp, it becomes positively charged and the leaves will open.

10. Further, if the negatively charged zinc plate is exposed to ultraviolet light, the leaves will close as the charges leaked away quickly. If the plate is positively charged, it becomes more positive upon UV rays irradiation and the leaves will open further.

11. From these observations, it was concluded that negatively charged electrons were emitted from the zinc plate under the action of ultraviolet light.

Lenard’s observation:
1. In 1902, Lenard studied this electron emission phenomenon in detail. The apparatus consists of two metallic plates A and C placed in an evacuated quartz bulb. The galvanometer G and battery B are connected in the circuit.

2. When ultraviolet light is incident on the negative plate C, an electric current flows in the circuit that is indicated by the deflection in the galvanometer. On other hand, if the positive plate is irradiated by the ultraviolet light, no current is observed in the circuit.

3. From these observations, it is concluded that when ultraviolet light falls on the negative plate, electrons are ejected from it which are attracted by the positive plate A. On reaching the positive plate through the evacuated bulb, the circuit is completed and the current flows in it.

4. Thus, the ultraviolet light falling on the negative plate causes the electron emission from the surface of the plate.

Question 3.
Explain the effect of potential difference on photoelectric current.
Answer:
Effect of potential difference on photoelectric current:
1. To study the effect of potential difference V between the electrodes on photoelectric current, the frequency and intensity of the incident light are kept constant. Initially the potential of A is kept positive with respect to C and the cathode is irradiated with the given light.

2. Now, the potential of A is increased and the corresponding photocurrent is noted. As the potential of A is increased, photocurrent is also increased. However a stage is reached where photocurrent reaches a saturation value (saturation current) at which all the photoelectrons from C are collected by A. This is represented by the flat portion of the graph between potential of A and photocurrent.

3. When a negative (retarding) potential is applied to A with respect to C, the current does not immediately drop to zero because the photoelectrons are emitted with some definite and different kinetic energies.

4. The kinetic energy of some of the photoelectrons is such that they could overcome the retarding electric field and reach the electrode A.

5. When the negative (retarding) potential of A is gradually increased, the photocurrent starts to decrease because more and more photoelectrons are being repelled away from reaching the electrode A. The photocurrent becomes zero at a particular negative potential V0, called stopping or cut-off potential.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-27

6. Stopping potential is that the value of the negative (retarding) potential given to the collecting electrode A which is just sufficient to stop the most energetic photoelectrons emitted and make the photocurrent zero.

7. At the stopping potential, even the most energetic electron is brought to rest. Therefore, the initial kinetic energy of the fastest electron (K_max ) is equal to the work done by the stopping potential to stop it (eV₀ ).
K_max = $\frac { 1 }{ 2 }$ ${ mv }_{ max }^{ 2 }$ = eV₀ …. (1)
Where v_max is the maximun speed of the emitted photoelectron.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-28
= 5.93 x 10⁵ $\sqrt { { V }_{ 0 } } $ …. (2)
From equation (1),
Kmax = eVo (in joule) (or) K_max = (V₀ ) (in eV)

8. From the graph, when the intensity of the incident light alone is increased, the saturation current also increases but the value of V₀ remains constant.

9. Thus, for a given frequency of the incident light, the stopping potential is independent of intensity of the incident light. This also implies that the maximum kinetic energy of the photoelectrons is independent of intensity of the incident light.

Question 4.
Explain how frequency of incident light varies with stopping potential.
Answer:
Effect of frequency of incident light on stopping potential:
1. To study the effect of frequency of incident light on stopping potential, the intensity of the incident light is kept constant. The variation of photocurrent with the collector electrode potential is studied for radiations of different frequencies and a graph drawn between them. From the graph, it is clear that stopping potential vary over different frequencies of incident light.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-29

2. Greater the frequency of the incident radiation, larger is the corresponding stopping potential. This implies that as the frequency is increased, the photoelectrons are emitted with greater kinetic energies so that the retarding potential needed to stop the photoelectrons is also greater.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-30

3. Now a graph is drawn between frequency and the stopping potential for different metals. From this graph, it is found that stopping potential varies linearly with frequency. Below a certain frequency called threshold frequency, no electrons are emitted; hence stopping potential is zero for that reason. But as the frequency is increased above threshold value, the stopping potential varies linearly with the frequency of incident light.

Question 5.
List out the laws of photoelectric effect.
Answer:
Laws of photoelectric effect:
1. For a given frequency of incident light, the number of photoelectrons emitted is directly proportional to the intensity of the incident light. The saturation current is also directly proportional to the intensity of incident light.

2. Maximum kinetic energy of the photo electrons is independent of intensity of the incident light.

3. Maximum kinetic energy of the photo electrons from a given metal is directly proportional to the frequency of incident light.

4. For a given surface, the emission of photoelectrons takes place only if the frequency of incident light is greater than a certain minimum frequency called the threshold frequency.

5. There is no time lag between incidence of light and ejection of photoelectrons.

Question 6.
Explain why photoelectric effect cannot be explained on the basis of wave nature of light.
Answer:
Failures of classical wave theory:
From Maxwell’s theory, light is an electromagnetic wave consisting of coupled electric and magnetic oscillations that move with the speed of light and exhibit typical wave behaviour. Let us try to explain the experimental observations of photoelectric effect using wave picture of light.

1. When light is incident on the target, there is a continuous supply of energy to the electrons. According to wave theory, light of greater intensity should impart greater kinetic energy to the liberated electrons (Here, Intensity of light is the energy delivered per unit area per unit time). But this does not happen. The experiments show that maximum kinetic energy of the photoelectrons does not depend on the intensity of the incident light.

2. According to wave theory, if a sufficiently intense beam of light is incident on the surface, electrons will be liberated from the surface of the target, however low the frequency of the radiation is. From the experiments, we know that photoelectric emission is not possible below a certain minimum frequency. Therefore, the wave theory fails to explain the existence of threshold frequency.

3. Since the energy of light is spread across the wavefront, the electrons which receive energy from it are large in number. Each electron needs considerable amount of time (a few hours) to get energy sufficient to overcome the work function and to get liberated from the surface. But experiments show that photoelectric emission is almost instantaneous process (the time lag is less than 10“9 s after the surface is illuminated) which could not be explained by wave theory.

Question 7.
Explain the quantum concept of light.
Answer:
Concept of quantization of energy:
Max Planck proposed quantum concept in 1900 in order to explain the thermal radiations emitted by a black body and the shape of its radiation curves. According to Planck, matter is composed of a large number of oscillating particles (atoms) which vibrate with different frequencies. Each atomic oscillator – which vibrates with its characteristic frequency – emits or absorbs electromagnetic radiation of the same frequency. It also says that

1. If an oscillator vibrates with frequency v, its energy can have only certain discrete values, given by the equation.
E_n = nhυ n = 1, 2, 3 ………..
where A is a constant, called Planck’s constant.

2. The oscillators emit or absorb energy in small packets or quanta and the energy of each quantum is E = hυ.
This implies that the energy of the oscillator is quantized – that is, energy is not continuous as believed in the wave picture. This is called quantization of energy.

Question 8.
Obtain Einstein’s photoelectric equation with necessary explanation. Einstein’s explanation of photoelectric equation:
Answer:
1. When a photon of energy hv is incident on a metal surface, it is completely absorbed by a single electron and the electron is ejected.

2. In this process, a part of the photon energy is used for the ejection of the electrons from the metal surface (photoelectric work function Φ₀) and the remaining energy as the kinetic energy of the ejected electron. From the law of conservation of energy,
hυ = Φ₀ + $\frac { 1 }{ 2 }$ mv² …… (1)
where m is the mass of the electron and u its velocity
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-31

3. If we reduce the frequency of the incident light, the speed or kinetic energy of photo electrons is also reduced. At some frequency V₀ of incident radiation, the photo electrons are ejected with almost zero kinetic energy. Then the equation (1) becomes
hυ₀ = Φ₀
where vQ is the threshold frequency. By rewriting the equation (1), we get
hυ = hυ₀ + $\frac { 1 }{ 2 }$ mv² …… (2)
The equation (2) is known as Einstein’s Photoelectric equation.
If the electron does not lose energy by internal collisions, then it is emitted with maximum kinetic energy K_max. Then
K_max = $\frac { 1 }{ 2 }$ ${ mv }_{ max }^{ 2 }$
where nmax is the maximum velocity of the electron ejected. The equation (1) is rearranged as follows:
K_max = hυ – Φ₀

Question 9.
Explain experimentally observed facts of photoelectric effect with the help of Einstein’s explanation.
Answer:
Explanation for the photoelectric effect:
The experimentally observed facts of photoelectric effect can be explained with the help of . Einstein’s photoelectric equation.

1. As each incident photon liberates one electron, then the increase of intensity of the light (the number of photons per unit area per unit time) increases the number of electrons emitted thereby increasing the photocurrent. The same has been experimentally observed.

2. From K_max = hυ – Φ₀, it is evident that Kmax is proportional to the frequency of the light and is independent of intensity of the light.

3. As given in Einstein’s photoelectric equation, there must be minimum energy (equal to the work function of the metal) for incident photons to liberate electrons from the metal surface. Below which, emission of electrons is not possible. Correspondingly, there exists minimum frequency called threshold frequency below which there is no photoelectric emission.

4. According to quantum concept, the transfer of photon energy to the electrons is instantaneous so that there is no time lag between incidence of photons and ejection of electrons.

Question 10.
Give the construction and working of photo emissive cell.
Answer:
Photo emissive cell:
Its working depends on the electron emission from a metal cathode due to irradiation of light or other radiations.
Construction:
1. It consists of an evacuated glass or quartz bulb in which two metallic electrodes – that is, a cathode and an anode are fixed.

2. The cathode C is semi-cylindrical in shape and is coated with a photo sensitive material. The anode A is a thin rod or wire kept along the axis of the semi-cylindrical cathode.

3. A potential difference is applied between the anode and the cathode through a galvanometer G.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-32

Working:
4. When cathode is illuminated, electrons are emitted from it. These electrons are attracted by anode and hence a current is produced which is measured by the galvanometer.

5. For a given cathode, the magnitude of the current depends on
(i) the intensity to incident radiation and (ii) the potential difference between anode and cathode.

Question 11.
Derive an expression for de Broglie wavelength of electrons.
Answer:
An electron of mass m is accelerated through a potential difference of V volt. The kinetic
energy acquired by the electron is given by
$\frac { 1 }{ 2 }$ mv² = evacuated
Therefore, the speed v of the electron is v = $\sqrt { \frac { 2eV }{ m } } $
Hence, the de Broglie wavelength of the electron is λ = $\frac { h }{ mv }$ = $\frac { h }{ \sqrt { 2emV } } $
Substituting the known values in the above equation, we get
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-33
For example, if an electron is accelerated through a potential difference of 100V, then its de Broglie wavelength is 1.227 A. Since the kinetic energy of the electron, K = eV, then the de Broglie wavelength associated with electron can be also written as
λ = $\frac { h }{ \sqrt { 2mK } } $

Question 12.
Briefly explain the principle and working of electron microscope.
Answer:
Electron Microscope:
Principle:
1. This is the direct application of wave nature of particles. The wave nature of the electron is used in the construction of microscope called electron microscope.

2. The resolving power of a microscope is inversely proportional to the wavelength of the radiation used for illuminating the object under study. Higher magnification as well as higher resolving power can be obtained by employing the waves of shorter wavelengths.

3. De Broglie wavelength of electron is very much less than (a few thousands less) that of the visible light being used in optical microscopes.

4. As a result, the microscopes employing de Broglie waves of electrons have very much higher resolving power than optical microscope.

5. Electron microscopes giving magnification more than 2,00.000 times are common in research laboratories.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-34
Working:
1. The electron beam passing across a suitably arranged either electric or magnetic fields undergoes divergence or convergence thereby focussing of the beam is done.

2. The electrons emitted from the source are accelerated by high potentials. The beam is made parallel by magnetic condenser lens. When the beam passes through the sample whose magnified image is needed, the beam carries the image of the sample.

3. With the help of magnetic objective lens and magnetic projector lens system, the magnified image is obtained on the screen. These electron microscopes are being used in almost all branches of science.

Question 13.
Describe briefly Davisson – Germer experiment which demonstrated the wave nature of electrons.
Answer:
Davisson – Germer experiment:
1. De Broglie hypothesis of matter waves was experimentally confirmed by Clinton Davisson and Lester Germer in 1927. They demonstrated that electron beams are diffracted when they fall on crystalline solids.

2. Since ciystal can act as a three-dimensional diffraction grating for matter waves, the electron waves incident on crystals are diffracted off in certain specific directions.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-35

3. The filament F is heated by a low tension (L.T.) battery. Electrons are emitted from the hot filament by thermionic emission. They are then accelerated due to the potential difference between the filament and the anode aluminium cylinder by a high tension (H.T.) battery.

4. Electron beam is collimated by using two thin aluminium diaphragms and is allowed to strike a single crystal of Nickel.

5. The electrons scattered by Ni atoms in different directions are received by the electron detector which measures the intensity of scattered electron beam.

6. The detector is rotatable in the plane of the paper so that the angle Φ between the incident
beam and the scattered beam can be changed at our will.

7. The intensity of the scattered electron beam is measured as a function of the angle θ.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-36

8. From the graph shows the variation of intensity of the scattered electrons with the angle 0 for the accelerating voltage of 54V. For a given accelerating voltage V, the scattered wave shows a peak or maximum at an angle of 50° to the incident electron beam.

This peak in intensity is attributed to the constructive interference of electrons diffracted from various atomic layers of the target material.

9. From the known value of interplanar spacing of Nickel, the wavelength of the electron wave has been experimentally calculated as 1.65 Å.

10. The wavelength can also be calculated from de Broglie relation for V = 54 V from equation.
λ = $\frac { 12.27 }{ \sqrt { V } } $ Å = $\frac { 12.27 }{ \sqrt { 54 } } $
λ = 1.67 Å

11. This value agrees well with the experimentally observed wavelength of 1.65 Å. Thus this experiment directly verifies de Broglie’s hypothesis of the wave nature of moving particles.

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Numerical problems

Question 1.
How many photons per second emanate from a 50 mW laser of 640 nm?
Answer:
P = 50 mW
λ = 640 nm
h = 6.6 x 10^-34 Js
c = 3 x 10⁸ms^-1
Number of photons emanate per second n_p = $\frac { P }{ E }$ =$\frac { Pλ }{ hc }$
= $\frac { 50\times { 10 }^{ 3 }\times 640\times { 10 }^{ -9 } }{ 6.6\times { 10 }^{ -34 }3\times { 10 }^{ 8 } } $ = $\frac { 32000\times { 10 }^{ -6 } }{ 19.8\times { 10 }^{ -26 } } $ = 1616.16 x 10^-6
n_p = 1.61 x 1010¹⁷ s^-1

Question 2.
Calculate the maximum kinetic energy and maximum velocity of the photoelectrons emitted when the stopping potential is 81 V for the photoelectric emission experiment.
Answer:
V₀ = 81 V
e= 1.6 x 10^-19 C
m = 9.1 x 10^-31 kg
Maximum kinetic energy of electron,
K_max = e^Vo
= 1.6 x 10^-19 x 81
= 129.6 x 10^-19
= 1.29 x 10^-17
K_max = 1.3 x 10^-17 J
aximum velocity of photoelectron,
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-37

Question 3.
Calculate the energies of the photons associated with the following radiation:
(i) violet light of 413 nm
(ii) X-rays of 0.1 nm
(iii) radio waves of 10 m.
Answer:
h = 6.6 x 10^-34 Js
c = 3 x 10⁸ ms^-1
Energy of photon, E = hυ
E = $\frac { hc }{ λ }$
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-38

Question 4.
A 150 W lamp emits light of mean wavelength of 5500 Å . If the efficiency is 12%, find out the number of photons emitted by the lamp in one second.
Answer:
P= 150W
λ = 5500 Å
h = 6.6 x 10^-34 Js
c = 3 x 10⁸ ms^-1
Number of photons emitted per second n = $\frac { pλ }{ hc }$
If the efficiency is 12%, η = $\frac { 12 }{ 100 }$ = 0.12
n = $\frac { pηλ }{ hc }$
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-40
n = 5 x 10¹⁹

Question 5.
How many photons of frequency 10¹⁴ Hz will make up 19.86 J of energy?
Answer:
Total energy emitted per second = Power x time
19.86 J = Power x is
∴ Power = 19.86 W
Number of photons, n = $\frac { p }{ E }$ = $\frac { p }{ hυ }$
= $\frac { 19.86 }{ 6.6\times { 10 }^{ -34 }\times { 10 }^{ 14 } } $ = 3.009 x 10²⁰
n = 3 x 10²⁰
n_p = 3 x 10²⁰

Question 6.
What should be the velocity of the electron so that its momentum equals that of 4000 Å wavelength photon.
Answer:
de-Broglie wavelength of electron
λ = $\frac { h }{ p }$
v = $\frac { h }{ mλ }$
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-41
v = 1811 ms^-1

Question 7.
When a light of frequency 9 x 10¹⁴ Hz is incident on a metal surface, photoelectrons are emitted with a maximum speed of 8 x 10⁵ms^-1. Determine the threshold frequency of the surface.
Answer:
According to Einstein’s photoelectric equation
$\frac { 1 }{ 2 }$ ${ mv }_{ max }^{ 2 }$ = h (υ-υ₀)
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-42
= 9 x 0¹⁴-4.4 x 10¹⁴
υ₀ = 4.6 x 10¹⁴ Hz

Question 8.
When a 6000 Å light falls on the cathode of a photo cell and produced photoemission. If a stopping potential of 0.8 V is required to stop emission of electron, then determine the:

frequency of the light
energy of the incident photon
work function of the cathode material
threshold frequency
net energy of the electron after it leaves the surface.

Answer:
Wavelength, λ = 6000 Å= 6000 x 10^-10 m
stopping potential, V₀ = 0.8 V
1. Frequency of the light, υ = $\frac { c }{ λ }$
= $\frac { 3\times { 10 }^{ 8 } }{ 600\times { 10 }^{ -10 } } $ = 5 x 10⁴ x 10^-18
υ = 5 x 10¹⁴ Hz

2. Energy of the incident photon,
E = hυ = 6.6 x 10^-34 x 5 x 10¹⁴
= 33 x 10^-20 J
= $\frac { 33\times { 10 }^{ -20 } }{ 1.6\times { 10 }^{ -19 } } $ = 20.625 x 10^-1
E = 2.06 eV

3. Work function of the cathode material.
W₀ = hυ – eV₀
= $\left(\frac{6.6 \times 10^{-34} \times 5 \times 10^{14}}{1.6 \times 10^{-19}}\right)$ – $\left(\frac{1.6 \times 10^{-19} \times 0.8}{1.6 \times 10^{-19}}\right)$ = 2.06-0.8
W₀ = 1.26 eV

4. Threshold frequency, W₀ = hυ₀
υ₀ = $\frac{W_{0}}{h}$ = $\frac{1.26 \times 1.6 \times 10^{-19}}{6.6 \times 10^{-34}}$ = 0.3055 x 10¹⁵
υ₀ = 3.05 x 10¹⁴ Hz

5. Net energy of the electron after it leaves the surface
E = (υ – υ₀)
= 6.6 x 10^-34 (5 x10¹⁴ – 3.06 x 10¹⁴
= 6.6 x 10^-34 x 1.94 x 10¹⁴
E = 12.804 x 10^-20 J
= $\frac{1.2804 \times 10^{-19}}{1.6 \times 10^{-19}}$
E = 0.8 e V

Question 9.
A 3310 Å photon liberates an electron from a material with energy 3 x 10^-19 J while another 5000 Å photon ejects an electron with energy 0.972×10^-19 J from the same material. Determine the value of Planck’s constant and the threshold wavelength of the material.
Answer:
They energy of ejected electron is given by E = $\frac { hc }{ λ }$ – $\frac { hc }{ { \lambda }_{ 0 } } $
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-43
Subtracting (2) from (1), we get

Threshold Wavelength,

Question 10.
At the given point of time, the earth receives energy from Sun at 4 cal cm^-2 min^-1. Determine the number of photons received on the surface of the Earth per cm² per minute. (Given : Mean wavelength of Sun light = 5500 Å)
Answer:
E= 4 calorie
= 4 x 4.184 J
λ = 5500 Å
Number of photons received on the surface of the earth, from E = nhυ
n = $\frac { E λ}{ hc }$
= $\frac{4 \times 4.184 \times 5500 \times 10^{-10}}{6.6 \times 10^{-34} \times 3 \times 10^{8}}$ = $\frac{9.2048 \times 10^{-10}}{19.8 \times 10^{-26}}$ = 4648 x 10¹⁶
= 4.648 x 10¹⁹
n = 4.65 x 10¹⁹

Question 11.
UV light of wavelength 1800 Å is incident on a lithium surface whose threshold wavelength 4965 Å. Determine the maximum energy of the electron emitted.
Answer:
λ = 1800 x 10^-10 m
λ₀ = 4965 x 10^-10m
h = 6.6 x 10^-34 Js
c = 3 x 10⁸ ms^-1
Maximum kinetic energy of electron,
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-45

Question 12.
Calculate the de Broglie wavelength of a proton whose kinetic energy is equal to 81.9 x 10^-15 J. (Given: mass of proton is 1836 times that of electron).
Answer:
m_p = 1.67 x 10^-27 kg
K.E = 81.9 x 10^-15 J
de-Broglie wavelength of proton, λ = $\frac { h }{ \sqrt { 2mK } } $
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-46
λ = 4 x 10^-14 m

Question 13.
A deuteron and an alpha particle are accelerated with the same potential. Which one of the two has (i) greater value of de Broglie wavelength associated with it and (ii) less kinetic energy? Explain.
Answer:
(i) Using de-Broglie wavelength formula, the dueteron and alpha particle are accelerated with same potential. So, both their velocities are same.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-47
(ii) For same potential of acceleration, KE is directly proportional to the ‘q’
Charge of duetron is +e
Charge of alpha is +2e
So, K_d = $\frac {{ K }_{α}}{ 2 }$
Charge of alpha particle is more than the duetron.

Question 14.
An electron is accelerated through a potential difference of 81V. What is the de Broglie wavelength associated with it? To which part of electromagnetic spectrum does this wavelength correspond?
Answer:
de-Broglie wavelength of an electron beam accelerated through a potential difference of V volts is
λ = $\frac { h }{ \sqrt { 2meV } } $ = $\frac { 1.23 }{ \sqrt { V } } $ nm
V = 81 V, so λ = $\frac { 1.23 }{ \sqrt { 81 } } $ x 10^-9 m
λ = 1.36 Å
X-ray is the part of electromagnetic spectrum does this wavelength corresponds. X-ray has the wavelengths ranging from about 10⁸ to 10^-12 m.

Question 15.
The ratio between the de Broglie wavelengths associated with protons, accelerated through a potential of 512 V and that of alpha particles accelerated through a potential of X volts is found to be one. Find the value of X.
Answer:
de-Broglie wavelength of accelerated charge particle
λ = $\frac { h }{ \sqrt { 2mqV } } $
λ ∝ $\frac { h }{ \sqrt { mqV } } $
Ratio of wavelength of proton and a-particle.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-48

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Additional Questions

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Multiple Choice Questions

Question 1.
The maximum kinetic energy of photoelectrons emitted from a surface when photons of
energy 3 eV fall on it is 4 eV. The stopping potential, in volt, is
(a) 2
(b) 4
(c) 6
(d) 10
Answer:
(b) 4
Hint:
Stopping potential, V₀ = $\frac { { K }_{ max } }{ e } $ = $\frac { 4eV }{ e }$ = 4v

Question 2.
If an electron and proton are propagating in the form of waves having the same λ, it implies that they have the same-
(a) energy
(b) momentum
(c) velocity
(d) angular momentum
Answer:
(b) momentum
Hint: Momentum, p = $\frac { h }{ λ }$
As both electron and proton have same λ, so they have the same momentum

Question 3.
An electron of mass m and charge e is accelerated from rest through a potential difference V in vacuum. Its final velocity will be-
(a) $\sqrt { \frac { 2eV }{ m } } $
(b) $\sqrt { \frac { eV }{ m } } $
(c) $\frac { ev }{ 2m }$
(d) $\frac { ev }{ m }$
Answer:
(a) $\sqrt { \frac { 2eV }{ m } } $
Hint:
K.E. gained by an electron when accelerated through a potential difference V,
$\frac { 1 }{ 2 }$ mv² = eV or v = $\sqrt { \frac { 2eV }{ m } } $

Question 4.
The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately
(a) 540 nm
(b) 400 nm
(c) 310 nm
(d) 220 nm
Answer:
(c) 310 nm
Hint:
λ₀ = $\frac { hc }{ W }$ = $\frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{4.0 \times 1.6 \times 10^{-19}}$ = m = 310 x 10^-9m = 310 nm

Question 5.
Sodium and copper have work function 2.3 eV and 4.5 eV respectively. Then, the ratio of their threshold wavelength is nearest to-
(a) 1 : 2
(b) 4 : 1
(c) 2 : 1
(d) 1 : 4
Answer:
(c) 2 : 1
Hint:
$\frac{\lambda_{0}(\mathrm{Na})}{\lambda_{0}(\mathrm{Cu})}$ = $\frac{\mathrm{W}_{0}(\mathrm{Cu})}{\mathrm{W}_{0}(\mathrm{Na})}$

Question 6.
The surface of a metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be 1.68 eV. The work function of the metal is (hc = 1240 eV nm)
(a) 3.09 eV
(b) 1.41 eV
(c) 1.51 eV
(d) 1.68 eV
Anwer:
(b) 1.41 eV
Hint:
K_max = $\frac { hc }{ λ }$ W₀ or W₀ = $\frac { hc }{ λ }$ – K_max
= $\frac { 1240 }{ 400 }$-1.68 = 3.10-1.68 = 1.42ev

Question 7.
4 eV is the energy of the incident photon and the work function is 2 eV. The stopping potential will be
(a) 2V
(b) 4V
(c) 6V
(d) 2√2V
Answer:
(d) 2√2V
Hint:
eV₀= hv- W₀ = 4eV – 2eV = 2eV
∴ V₀= $\frac { 2ev }{ e }$ = 2v

Question 8.
A light having wavelength 300 nm falls on a metal surface work function of metal is 2.54 eV. What is stopping potential?
(a) 1.4 V
(b) 2.59 V
(c) 1.60 V
(d) 1.29 V
Answer:
(a) 1.4 V
Hint:
eV₀ = hu – W₀ = 2eV – 0.6 eV = 1.4 eV
∴ V₀= $\frac { 1.4eV }{ e }$ = 1.4eV

Question 9.
If the kinetic energy of a free electron doubles, its de-Broglie wavelength changes by the factor
(a) $\frac { 1 }{ 2 }$
(b) 2
(c) $\frac { 1 }{ √2 }$
(d) √2
Answer:
(c) $\frac { 1 }{ √2 }$
Hint:
λ = $\frac{h}{\sqrt{2 m \mathrm{K}}}$
When kinetic energy is doubled, λ’ = $\frac{h}{\sqrt{2 m \times 2 K}}$ = $\frac { 1 }{ √2 }$λ

Question 10.
If the kinetic energy of a particle is increased by 16 times, the percentage change in the de-Broglie wavelength of the particle is
(a) 25%
(b) 75%
(c) 60%
(d) 50%
Answer:
(b) 75%
Hint:
λ = $\frac{h}{\sqrt{2 m \mathrm{K}}}$ ; $\frac{h}{\sqrt{2 m \times 16 K}}$ = $\frac { λ }{ 4 }$
% change in de-Broglie wavelength, $\frac { λ-λ’ }{ λ }$ = [1-$\frac { λ }{ λ’ }$] x 100 [1-$\frac { 1 }{ 4 }$] x 100 = 75%

Question 11.
When a proton is accelerated through IV, then its kinetic energy will be
(a) 1 eV
(b) 13.6 eV
(c) 1840 eV
(d) 0.54 eV
Answer:
(a) 1 eV
Hint:
K = qV = e x 1V= 1 eV

Question 12.
The kinetic energy of an electron, which is accelerated in the potential difference of 100 volts, is
(a) 416.6 cal
(b) 6.636 cal
(c) 1.602 x 10^-17 J
(d) 1.6 x 104 J
Answer:
(c) 1.602 x 10^-17 J
Hint:
K = eV = 1.602 x 10(c) 1.602 x 10^-19 x 100 J
= 1.602 x 10(c) 1.602 x 10^-17 J

Question 13.
Kinetic energy of emitted electron depends upon
(a) frequency
(b) intensity
(c) nature of atmosphere surrounding the electron
(d) none of these
Answer:
(a) frequency
Hint:
Kinetic energy of emitted electron depends on the frequency of incident radiation.

Question 14.
The work function of photometal is 6.626 eV. What is the threshold wavelength?
(a) 3921 Å
(b) 1875 Å
(c) 1867 Å
(d) 4433 Å
Answer:
(b) 1875 Å
Hint:
λ₀ = $\frac { hc }{{ W }_{ 0 }}$ = $\frac{6.63 \times 10^{-34} \times 3 \times 10^{8} \times 10^{10}}{6.626 \times 1.6 \times 10^{-19}}$ Å = 1875 Å

Question 15.
The number of photo-electrons emitted for light of a frequency υ (higher than the threshold frequency υ₀) is proportional to
(a) Threshold frequency (υ₀)
(b) Intensity of light
(c) Frequency of light (υ)
(d) υ – υ₀
Answer:
(b) Intensity of light
Hint:
Photoelectric current oc Intensity of incident light

Question 16.
The speed of an electron having a wavelength of 10^-10 m is
(a) 7.25 x 10⁶ ms^-1
(b) 6.26 x 10⁶ ms^-1
(c) 5.25 x 10⁶ ms^-1
(d) 4.24 x 10⁶ ms^-1
Answer:
(a) 7.25 x 10⁶ ms^-1
Hint:
As λ = $\frac { h }{ mv }$
∴ v = $\frac { h }{ mλ }$ = $\frac{6.6 \times 10^{-34}}{9.1 \times 10^{-31} \times 10^{-10}}$ = 7.25 x 10⁶ ms^-1

Question 17.
If an electron and a photon propagate in the form of waves having the same wavelength, it implies that they have the same
(a) energy
(b) momentum
(c) angular momentum
(d) velocity
Answer:
(b) momentum
Hint:
As both electron and photon have same de-Broglie wavelength (λ = h /p), so they have the same momentum P.

Question 18.
Electron volt is a unit of
(a) Energy
(b) potential
(c) current
(d) charge
Answer:
(a) Energy
Hint:
Electron volt is a unit of energy

Question 19.
Photon of frequency u has a momentum associated with it. If c is the velocity of radiation, then the momentum is
(a) $\frac { hυ }{ c }$
(b) $\frac { υ }{ c }$
(c) hυc
(d) $\frac { h }{ { c }^{ 2 } } $
Answer:
(a) $\frac { hυ }{ c }$
Hint:
P = $\frac { E }{ { c }^{ 2 } } $ = $\frac { hυ }{ c }$

Question 20.
The time taken by a photoelectron to come out after photon strikes is approximately
(a) 10^-14 s
(b) 10^-10 s
(c) 10^-16 s
(d) 10^-1 s
Answer:
(b) 10^-10 s
Hint:
The time lag between the incident of photon and the emission of photoelectrons is 10^-10 s approximately.

Question 21.
Cathode rays consist of
(a) photons
(b) electrons
(c) protons
(d) α-particles
Answer:
(b) electrons

Question 22.
The momentum of photon whose frequency is f is
(a) $\frac { hf }{ c }$
(b) $\frac { hc }{ f }$
(c) $\frac { h }{ f }$
(d) $\frac { c }{ hf }$
Answer:
(a) $\frac { hf }{ c }$
Hint:
p = mc = $\frac { { mc }^{ 2 } }{ { c } } $ = $\frac { hf }{ c }$

Question 23.
The energy of photon of wavelength λ is
(a) $\frac { hc }{ λ }$
(b) hλc
(c) $\frac { λ }{ hc }$
(d) $\frac { hλ }{ c }$
Answer:
(a) $\frac { hc }{ λ }$
Hint:
E = hυ = $\frac { hc }{ λ }$

Question 24.
The ratio of the energy of a photon with λ = 150 nm to that with λ = 300 nm is
(a) 2
(b) $\frac { 1 }{ 4 }$
(c) 2
(d) $\frac { 1 }{ 2 }$
Answer:
(a) 2
Hint:
$\frac {{ E }_{ 1 }}{ { E }_{ 2 } }$ = $\frac {{ λ }_{ 2 }}{ { λ }_{ 1 } }$ = $\frac { 300 }{ 150 }$ = 2

Question 25.
Photons of 5.5 eV energy fall on the surface of the metal emitting photoelectrons of maximum kinetic energy 4.0 eV. The stopping voltage required for these electrons is
(a) 5.5 V
(b) 1.5 V
(c) 9.5 V
(d) 4.0 V
Answer:
(d) 4.0 V
Hint:
Stopping potential = $\frac { { K }_{ max } }{ e } $ = $\frac { 4.0ev }{ e }$ = 4.0V

Question 26.
The wavelength of photon is proportional to (where υ = frequency)
(a) υ
(b) √υ
(c) $\frac { 1 }{ √υ }$
(d) $\frac { 1 }{ υ }$
Answer:
(d) $\frac { 1 }{ υ }$
Hint:
λ = $\frac { c }{ υ }$ i.e., λ ∝ $\frac { 1 }{ υ }$

Question 27.
What is the energy of a photon whose wavelength is 6840 Å?
(a) 1.81 eV
(b) 3.6 eV
(c) – 13.6 eV
(d) 12.1 eV
Answer:
(a) 1.81 eV
Hint:
E = hυ = $\frac { hc }{ λ }$ = $\frac { 12400ev Å }{ 8840 Å }$ = 1.81 eV

Question 28.
Momentum of photon of wavelength λ is
(a) $\frac { hυ }{ c }$
(b) zero
(c) $\frac { hλ }{{ c }^{ 2 }}$
(d) $\frac { hλ }{c}$
Answer:
(a) $\frac { hυ }{ c }$
Hint:
p = mc = $\frac {{ mc }^{ 2 }}{c}$ = $\frac { hυ }{ c }$

Question 29.
The momentum of a photon of energy 1 MeV in kg m/s will be
(a) 5 x 10^-22
(b) 0.33 x 10⁶
(c) 7 x 10^-24
(d) 10^-22
Answer:
(a) 5 x 10^-22
Hint:
P = $\frac { E }{ c }$ = $\frac{1 \mathrm{MeV}}{3 \times 10^{8} \mathrm{ms}^{-1}}$ = $\frac{1.6 \times 10^{-13} \mathrm{J}}{3 \times 10^{8} \mathrm{ms}^{-1}}$ = 5.33 x 10^-22 Kg ms^-1

Question 30.
If we consider electrons and photons of same wavelength then will have same
(a) momentum
(b) angular momentum
(c) energy
(d) velocity
Answer:
(a) momentum
Hint:
As p = h/λ, so electrons and photons having the same wavelength λ will have the same momentum p.

Question 31.
Photoelectric effect can be explained by
(a) corpusular theory of light
(b) wave nature of light
(c) Bohr’s theory
(d) quantum theory of light
Answer:
(d) quantum theory of light

Question 32.
Which of the following waves can produce photoelectric effect?
(a) ultrasound
(b) infrared
(c) radiowaves
(d) X-rays
Answer:
(d) X-rays
Hint:
Electromagnetic radiation, being of high frequency such as X-rays can produce photoelectric effect.

Question 33.
Which light when falls on a metal will emit photoelectrons?
(a) uv radiation
(b) infrared radiation
(c) radio waves
(d) microwaves
Answer:
(a) uv radiation
Hint:
Ultraviolet radiation, being of high frequency, can emit photoelectrons from metals.

Question 34.
In photoelectric effect, the KE of electrons emitted from the metal surface depends upon
(a) intensity of light
(b) frequency of incident light
(c) velocity of incident light
(d) both intensity and velocity of light
Answer:
(b) frequency of incident light
Hint:
The kinetic energy of photoelectrons depends upon the frequency of incident light.

Question 35.
In photoelectric effect, electrons are ejected from metals, if the incident light has a certain minimum
(a) wavelength
(b) frequency
(c) amplitude
(d) angle of incidence
Answer:
(b) frequency
Hint:
For photoelectric emission, the incident light must have a certain minimum frequency, called threshold frequency.

Question 36.
Number of ejected photoelectrons increases with increases
(a) in intensity of light
(b) in wavelength of light
(c) in frequency of light
(d) never
Answer:
(a) in intensity of light
Hint:
Number of ejected photoelectrons increases with the increase in intensity of light.

Question 37.
By photoelectric effect, Einstein proved
(a) E = hυ
(b) K.E. = $\frac { 1 }{ 2 }$mv²
(c) E = mc²
(d) E = $\frac {{ -Rhc }^{ 2 }}{{ n }^{ 2 }}$
Answer:
(a) E = hυ
Hint:
Einstein explained photoelectric effect on the basis of planck’s quantum theory of radiation and hence supported the relation : E = hυ

Question 38.
A photocell employs photoelectric effect to convert
(a) change in the frequency of light into a change in the electric current
(b) Change in the frequency of light into a change in electric voltage
(c) Change in the intensity of illumination into a change in photoelectric current
(d) Change in the intensity of illumination into a change in the work function of the photo cathode
Answer:
(c) Change in the intensity of illumination into a change in photoelectric current
Hint:
It indicates that threshold frequency is greater than that of ultraviolet light. As X-rays have greater frequency than uv rays, so they can cause photoelectric effect.

Question 39.
When ultraviolet rays incident on metal plate there photoelectric effect does not occur, it occurs by incident of
(a) infrared rays
(b) X-rays
(c) radio waves
(d) microwave
Answer:
(b) X-rays
Hint:
It indicates that threshold frequency is greater than that of ultraviolet light. As X-rays have greater frequency than UV rays, so they can cause photoelectric effect.

Question 40.
The threshold frequency for photoelectric effect on sodiune corresponds to a wavelength of 5000 Å. Its function is
(a) 4 x 10^-19 J
(b) 1J
(c) 2 x 10^-19 J
(d) 3 x 10^-19 J
Answer:
(a) 4 x 10^-19 J
Hint:
W₀ = $\frac { hc }{{ λ }_{ 0 }}$ = $\frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{5000 \times 10^{-10}}$ J = 4 x 10^-19 J

Question 41.
The photoelectric work function for a metal surface is 4.125 eV. The cut off wavelength for this surface is
(a) 3000 Å
(b) 2062.5 Å
(c) 4125 Å
(d) 6000 Å
Answer:
(a) 3000 Å
Hint:
λ₀ = $\frac { hc }{{ W }_{ 0 }}$ = $\frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{4.125 \times 1.6 \times 10^{-19}}$ m = 3 x 10^-7 m = 3000 Å

Question 42.
Ultraviolet radiations of 6.2 eV falls on an aluminium surface. Kinetic energy of fastest electrons emitted is (work function = 4.2 eV)
(a) 3.2 x 10^-21 J
(b) 3.2 x 10^-19 J
(c) 7 x 10^-25 J
(d) 9 x 10^-32 J
Answer:
(b) 3.2 x 10^-19 J
Hint:
K_max = hυ- W₀ = 6.2 eV – 4.2 eV
= 2.0 eV = 2.0 x 1.6 x 10^-19 J =3.2 x 10^-19 J

Question 43.
The de-Broglie wavelength of a tennis ball of mass 60g moving with a velocity of 10 ms^-1 is approximately (planck’s constant, h = 6.63 x 10^-34 Js)
(a) 10^-33 m
(b) 10^-31 m
(c) 10^-16 m
(d) 10^-25 m
Answer:
(a) 10^-33 m
Hint:
λ = $\frac { h }{ mv }$ = $\frac{6.63 \times 10^{-34}}{60 \times 10^{-3} \times 10}$ ≈ 10^-33 m

Question 44.
The wavelength of de-Broglie wave is 2 μm, then its momentum (h = 6.63 x 10^-34 Js) is
(a) 3.315 x 10^-28 kg ms^-1
(b) 1.66 x 10^-28 kg ms^-1
(c) 4.97 x 10^-28 kg ms^-1
(d) 9.9 x 10^-28 kg ms^-1
Answer:
(a) 3.315 x 10^-28 kg ms^-1
Hint:
p = $\frac { h }{ λ }$ = $\frac{6.03 \times 10^{-34} \mathrm{Js}}{2 \times 10^{-6} \mathrm{m}}$ = 3.315 x 10^-28 kg ms^-1

Question 45.
What is de-Broglie wavelength of electron having energy 10 KeV?
(a) 0.12 Å
(b) 1.2 Å
(c) 12.2 Å
(d) none of these
Answer:
(a) 0.12 Å
Hint:
λ = $\frac { 12.3 }{ √v }$ Å = $\frac { 12.3 }{ \sqrt { 10\times { 10 }^{ 3 } } } $ = 0.12Å

Question 46.
Which one of the following property does not support wave theory of light?
(a) Light obeys laws of reflection and refraction
(b) Light waves get polarised
(c) Light shows photoelectric effect
(d) Light shows interference
Answer:
(c) Light shows photoelectric effect
Hint:
Photoelectric effect cannot be explained on the basis of wave theory of light.

Question 47.
de-Broglie wavelength λ associated with neutrons is related with absolute temperature T as
(a) λ ∝ T
(b) λ ∝ $\frac { 1 }{ T }$
(c) λ ∝ $\frac { 1 }{ √T }$
(d) λ ∝ T²Answer:
(c) λ ∝ $\frac { 1 }{ √T }$
Hint:
λ = $\frac { h }{ \sqrt { 2mK } } $ = $\frac { h }{ \sqrt { 3mKT } } $ ⇒ λ ∝ $\frac { 1 }{ √T }$

Question 48.
As the intensity of incident light increases
(a) kinetic energy of emitted photoelectrons increases
(b) photoelectric current decreases
(c) photoelectric current increases
(d) kinetic energy of emitted photoelectrons decreases
Answer:
(c) photoelectric current increases
Hint:
As the intensity of incident light increases, photoelectric current increases.

Question 49.
The de Broglie wave corresponding to a particle of mass m and velocity u has a wavelength associated with it
(a) $\frac { h }{ mυ }$
(b) hmυ
(c) $\frac { mh }{ υ }$
(d) $\frac { m }{ hυ }$
Answer:
(a) $\frac { h }{ mυ }$
Hint:
de-Broglie wavelength, λ = $\frac { h }{ p }$ = $\frac { h }{ mυ }$

Question 50.
If particles are moving with same velocity, then which has maximum de-broglie wavelength?
(a) Proton
(b) α-particle
(c) Nevtron
(d) β-particle
Answer:
(d) β-particle
Hint:
As λ = h/mv, of the given particles β – particle is the lightest, so it will have maximum de-Broglie wavelength.

Question 51.
The dual nature of light is exhibited by
(a) diffraction and photoelectric effect
(b) photoelectric effect
(c) refraction and interference
(d) diffraction and reflection
Answer:
(a) diffraction and photoelectric effect
Hint:
Diffraction exhibits wave nature while photoelectric effect exhibits particle nature. Hence these two phenomena exhibit dual nature of light.

Question 52.
If the momentum of a particle is doubled, then its de-Broglie wavelength will-
(a) remain unchanged
(b) become four time
(c) become two times
(d) become half
Answer:
(d) become half
Hint:
As λ = $\frac { h }{ p }$ when momentum p is doubled, wavelength will become half the initial value.

Question 53.
Moving with the same velocity, which of the following has the longest de-Broglie wavelength?
(a) β – particle
(b) α – particle
(c) proton
(d) neutron
Answer:
(a) β – particle
Hint:
λ = $\frac { h }{ mv }$ λ ∝ $\frac { 1 }{ m}$
As β – particle (an electron) has the smallest mass, so it has the longest de-Broglie wavelength.

Question 54.
What is the de-Broglie wavelength of the a-particle accelerated through a potential difference of V volt? (mass of a-particle = 6.6455 x 10^-27 kg)
(a) $\frac { 0.287 }{ √V }$ Å
(b) $\frac { 12.27 }{ √V }$ Å
(c) $\frac { 0.101 }{ √V }$ Å
(d) $\frac { 0.202 }{ √V }$ Å
Answer:
(c) $\frac { 0.101 }{ √V }$ Å
Hint:
K = qV = 2eV
λ = $\frac { h }{ \sqrt { 2mK } } $ = $\frac { h }{ \sqrt { 2m\times 2eV\quad } } $ = $\frac { h }{ \sqrt { 4meV } } $
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-49

Question 55.
A proton and an a – particle are accelerated through the same potential difference. The ratio of de-Broglie wavelength of proton to the de-Broglie wavelength of alpha particle will be
(a) 1 : 2
(b) 2√2 :1
(c) 2 : 1
(d) 1:1
Answer:
(b) 2√2 :1
Hint:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-50

Question 56.
Proton and α – particle have the same de-Broglie wavelength. What is same for both of them?
(a) Time period
(b) Energy
(c) Frequency
(d) Momentum
Answer:
(d) Momentum
Hint:
λ = h/p, when wavelength λ is same, momentump is also same.

Question 57.
The shortest wavelength of X-ray emitted from an X-ray tube depends upon.
(a) the current in the tube
(b) the voltage applied to the tube
(c) the nature of the gas in the tube
(d) the atomic number of the target material
Answer:
(b) the voltage applied to the tube
Hint:
λ_min = $\frac { hc }{ eV }$ i.e.,λ_min ∝ $\frac { 1 }{ V }$

Question 58.
An X-ray tube operates on 30 kV. The minimum wavelength emitted is h = 6.6 x 10^-34 Js, c = 3 x 10⁸ m/s, e = 1.6 x 10^-19C.
(a) 6.6 Å
(b) 0.133 Å
(c) 1.2 Å
(d) 0.4 Å
Answer:
(d) 0.4 Å
Hint:
λ_min = $\frac { hc }{ eV }$ = $\frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{1.6 \times 10^{-19} \times 30 \times 10^{3}}$ m = 0.4 Å

Question 59.
The potential difference between the cathode and the target in a coolidge tube is 120 kV. What can be the minimum wavelength (in Å) of the X-rays emitted by this tube?
(a) 0.4 Å
(b) 0.3 Å
(c) 0.2 Å
(d) 0.1 Å
Answer:
(d) 0.1 Å
Hint:
λ_min = $\frac { 12375 }{ V }$ = Å = $\frac { 12375 }{{ 120×10 }^{3}}$ Å = 0.1Å

Question 60.
The work function for Al, K and Pt is 4.28 eV, 2.30 eV and 5.65 eV respectively. Their respective threshold frequencies would be
(a) pt > AL > K
(b) Al > pt > K
(c) K > AL > pt
(d) Al > K > pt
Answer:
(a) pt > AL > K
Hint:
As W₀ = hv₀ i.e., W₀ ∝ V₀
V₀ (pt) >₀ (AL) >V₀ (K)

Question 61.
Among the following four spectral regions, the photons has the highest energy in
(a) Infrared
(b) Violet
(c) Red
(d) Blue
Answer:
(b) Violet
Hint:
E = $\frac { hc }{ λ }$ Photon in violet region has least λ and hence highest energy.

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Short Answer Questions

Question 1.
Define electron volt. Express it value in joule.
Answer:
It is the kinetic energy gained by an electron when it is accelerated through a potential difference of 1 volt.
1 eV = 1.6 x 10^-19 J
1 MeV = 1.6 x 10^-13J

Question 2.
What are photoelectrons?
Answer:
These are the electrons emitted from a metal surface when it is exposed to electro magnetic radiations of a suitable frequency.

Question 3.
Define the term ‘stopping potential’ in relation to photoelectric effect.
Answer:
The minimum negative potential given to the anode of a photo-cell for which the photoelectric current becomes zero is called stopping potential.

Question 4.
Give some important uses of photo-cells.
Answer:
Applications of photo cells:

Photo cells have many applications, especially as switches and sensors.
Automatic lights that turn on when it gets dark use photocells, as well as street lights that switch on and off according to whether it is night or day.
Photo cells are used for reproduction of sound in motion pictures and are used as timers to measure the speeds of athletes during a race.

Question 5.
Why is a photo-cell also called an electric eye?
Answer:
Like an eye, a photo-cell can distinguish between a weak and an intense light. But a photocell gives a measure of light intensity in terms of photoelectric current. So it is also called an electric eye.

Question 6.
On what principle is an electron microscope based?
Answer:
As electron microscope exploits the wave nature of an accelerated beam of electrons (having a very small wavelength) to provide high magnifying and resolving powers.

Question 7.
What are X-ray spectra?
Answer:
X-rays are produced when fast moving electrons strike the metal target. The intensity of the X-rays when plotted against its wavelength gives a curve called X-ray spectrum.

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Long Answer Questions

Question 1.
Describe an experimental arrangement to study photoelectric effect.
Answer:
Experimental setup:
1. The apparatus is employed to study the phenomenon of photoelectric effect in detail .

2. S is a source of electromagnetic waves of known and variable frequency v and intensity I. C is the cathode (negative electrode) made up of photosensitive material and is used to emit electrons.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-51

3. The anode (positive electrode) A collects the electrons emitted from C. These electrodes are taken in an evacuated glass envelope with a quartz window that permits the passage of ultraviolet and visible light.

4. The necessary potential difference between C and A is provided by high tension battery B which is connected across a potential divider arrangement PQ through a key K. C is connected to the centre terminal while A to the sliding contact J of the potential divider.

5. The plate A can be maintained at a desired positive or negative potential with respect to C. To measure both positive and negative potential of A with respect to C, the voltmeter is designed to have its zero marking at the centre and is connected between A and C. The current is measured by a micro ammeter μA in series.

6. If there is no light falling on the cathode C, no photoelectrons are emitted and the microammeter reads zero. When ultraviolet or visible light is allowed to fall on C, the photoelectrons are liberated and are attracted towards anode.

7. As a result, the photoelectric current is setup in the circuit which is measured using micro ammeter.

8. The variation of photocurrent with respect to-

intensity of incident light
the potential difference between the electrodes
the nature of the material and
frequency of incident light can be studied with the help of this apparatus.

Question 2.
Write down the characteristics of photons.
Answer:
Characteristics of photons:
According to particle nature of light, photons are the basic constituents of any radiation and possess the following characteristic properties:
(i) The photons of light of frequency v and wavelength λ will have energy, given by
E = hυ = $\frac { hc }{ λ }$.

(ii) The energy of a photon is determined by the frequency of the radiation and not by its intensity and the intensity has no relation with the energy of the individual photons in the beam.

(iii) The photons travel with the velocity of light and its momentum is given by p

(iv) Since photons are electrically neutral, they are unaffected by electric and magnetic fields.

(v) When a photon interacts with matter (photon-electron collision), the total energy, total linear momentum and angular momentum are conserved. Since photon may be absorbed or a new photon may be produced in such interactions, the number of photons may not be conserved

Question 3.
Briefly explain the nature of light, (wave-particle duality)
Answer:
The nature of light: wave – particle duality
We have learnt that wave nature of light explains phenomena such as interference, diffraction and polarization. Certain phenomena like black body radiation, photoelectric effect can be explained by assigning particle nature to light. Therefore, both theories have enough experimental evidences.

In the past, many scientific theories have been either revised or discarded when they contradicted with new experimental results. Here, two different theories are needed to answer the question: what is nature of light?
It is therefore concluded that light possesses dual nature, that of both particle and wave. It behaves like a wave at some circumstances and it behaves like a particle at some other circumstances.

In other words, light behaves as a wave during its propagation and behaves as a particle during its interaction with matter. Both theories are necessary for complete description of physical phenomena. Hence, the wave nature and quantum nature complement each other.

Question 4.
Derive de-Broglie wave equation (wavelength) for a material particle.
Answer:
De Broglie wave length:
The momentum of photon of frequency v is given by
p = $\frac { hυ }{ c }$ = $\frac { h }{ λ }$ since c = υλ
The wavelength of a photon in terms of its momentum is
λ = $\frac { h }{ p }$ …(1)
According to de Broglie, the above equation is completely a general one and this is applicable to material particles as well. Therefore, for a particle of mass m travelling with speed v , the wavelength is given by
λ = $\frac { h }{ mv }$ = $\frac { h }{ p }$ ….. (2)
This wavelength of the matter waves is known as de Broglie wavelength. This equation relates the wave character (the wave length λ) and the particle character (the momentum p) through Planck’s constant.

Question 5.
Explain the production of X-rays.
Answer:
Production of x-rays:
X-rays are produced in x-ray tube which is essentially a discharge tube. A tungsten filament F is heated to incandescence by a battery. As a result, electrons are emitted from it by thermionic emission.
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-52
The electrons are accelerated to high speeds by the voltage applied between the filament F and the anode. The target materials like tungsten, molybdenum are embedded in the face of the solid copper anode. The face of the target is inclined at an angle with respect to the electron beam so that x-rays can leave the tube through its side.

When high-speed electrons strike the target, they are decelerated suddenly and lose their kinetic energy. As a result, x-ray photons are produced. Since most of the kinetic energy of the bombarding electrons gets converted into heat, targets made of high-meltmg-point metals and a cooling system are usually employed.

Question 6.
Briefly explain the concept of continuous X-ray spectra.
Answer:
Continuous x-ray spectra:
When a fast moving electron penetrates and approaches a target nucleus, the interaction between the electron and the nucleus either accelerates or decelerates it which results in a change of path of the electron. The radiation produced from such decelerating electron is called Bremsstrahlung or braking radiation
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-53

The energy of the photon emitted is equal to the loss of kinetic energy of the electron. Since an electron may lose part or all of its energy to the photon, the photons are emitted with all possible energies (or frequencies). The continuous x-ray spectrum is due to such radiations.

When an electron gives up all its energy, then the photon is emitted with highest frequency υ₀ (or lowest wavelength λ₀ ). The initial kinetic energy of an electron is given by eV where V is the accelerating voltage. Therefore, we have
hυ₀ = eV (or) $\frac { hc }{{ λ }_{0}}$ = ev
λ₀ = $\frac { hc }{eV}$
where λ₀ is the cut-off wavelength. Substituting the known values in the above equation, we get
λ₀ = $\frac { 122400 }{V}$ Å
The relation given by equation is known as the Duane – Hunt formula.
The value of λ₀ depends only on the accelerating potential and is same for all targets. This is in good agreement with the experimental results. Thus, the production of continuous x-ray spectrum and the origin of cut – off wavelength can be explained on the basis of photon theory of radiation.

Question 7.
Write down the applications of X-rays.
Answer:
Applications of x-rays:
X-rays are being used in many fields. Let us list a few of them.
1. Medical diagnosis:
X-rays can pass through flesh more easily than through bones. Thus an x-ray radiograph containing a deep shadow of the bones and a light shadow of the flesh may be obtained. X-ray radiographs are used to detect fractures, foreign bodies, diseased organs etc.

2. Medical therapy:
Since x-rays can kill diseased tissues, they are employed to cure skin diseases, malignant tumours etc.

3. Industry:
X-rays are used to check for flaws in welded joints, motor tyres, tennis balls and wood. At the custom post, they are used for detection of contraband goods.

4. Scientific research:
X-ray diffraction is important tool to study the structure of the crystalline materials – that is, the arrangement of atoms and molecules in crystals.

Samacheer Kalvi 12th Physics Dual Nature of Radiation and Matter Additional Numerical Problems

Question 1.
If a light of wavelength 4950 Å is viewed as a continuous flow of photons, what is the energy of each photon in eV? (Given h = 6.6 x 10^-34 Js, c = 3 x 10⁸ ms^-1)
Solution:
Here λ = 4950 Å = 4950 x 10^-10 m
Energy of each photon,
E = $\frac { hc }{λ}$ = $\frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{4950 \times 10^{-10}}$ = 4 x 10^-19 J
= $\frac{4 \times 10^{-19}}{1.6 \times 10^{-19}}$eV
E = 2.5 eV

Question 2.
Monochromatic light of frequency 6 x 10¹⁴ Hz is produced by a laser. The power emitted is 2 x 10^-3w.
(i) What is the energy of each photon in the light?
(ii) How many photons per second, on the average, are emitted by the source?
Solution:
(i) Energy of each photon,
E = hυ = 6.6 x 10^-34 x 6 x 10¹⁴
E = 3.98 x 10^-19J
(ii) If N is the number of photons emitted per second by the source, then
Power transmitted in the beam = N x energy of each photon
P = N
N = $\frac { P }{ E }$ = $\frac{2 \times 10^{-3}}{3.98 \times 10^{-19}}$
N = 5 x 10¹⁵ Photons per second.

Question 3.
Light of wavelength 5000 Å falls on a metal surface of work function 1.9 eV. Find:
(i) the energy of photons in eV
(ii) the K.E of photoelectrons and
(iii) the stopping potential.
Solution:
Here λ = 5000 Å = 5 x 10^-7 m
W₀ = 1.9 ev
(i) Energy of a photon,
E = $\frac { hc }{λ}$ = $\frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{5 \times 10^{-7}}$ J = $\frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{5 \times 10^{-7} \times 1.6 \times 10^{-19}} e V$ eV
E = 2.475 eV
(ii) K.E of a photoelectron,
K.E = hυ – W₀ = 2.475 – 1.9 = 0.575 eV
(iii) Let V₀ be the stopping potential. Then
eV₀ = $\frac { 1 }{ 2 }$ mv² = K.E of a photoelectron
V₀ = $\frac { 0.575 }{ e }$ eV
V₀ = 0.575 V

Question 4.
If photoelectrons are to be emitted from a potassium surface with a speed 6 x 10⁶ ms^-1, what frequency of radiation must be used? (Threshold frequency for potassium is 4.22 x 10¹⁴ Hz, h = 6.6 x 10^-34 Js, me = 9.1 x 10^-31 kg)
Solution:
Here, v = 6 x 10⁶ ms^-1
V₀ = 4.22 x 10¹⁴ Hz
From Einstein’s photoelectric equation,
k.E = $\frac { 1 }{ 2 }$ mv² = h (υ – υ₀)
υ = $\frac { 1 }{ 2 }$ $\frac {{ mv }^{2}}{ h }$ + υ₀
= $\frac { 1 }{ 2 }$ x $\frac{9.1 \times 10^{-31}+\left(6 \times 10^{6}\right)^{2}}{6.6 \times 10^{-34}}$ + 4. 22 x 10^-14
= (2.48 x 10¹⁴) + (4. 22 x 10¹⁴)
υ = 6.7 x10¹⁴Hz

Question 5.
The photoelectric cut-off voltage in a certain experiment 1.5 V. What is the maximum kinetic energy of photoelectrons emitted?
Solution:
Here V₀ = 1.5 V
K_max = eV₀ = 1.5 eV
= 1.5 x 1.6 x 10^-19 J
K_max = 24 x 10^-19 J

Question 6.
What is the (a) momentum, (b) speed, and (c) de-Broglie wavelength of an electron with kinetic energy of 120 eV.
Solution:
Kinetic energy, K.E = 120 eV = 120 x 1.6 x 10^-19
K = K.E = 1.92 x 10^-17 J
(a) Momentum of an electron, P = $\sqrt { 2mK } $
P = $\sqrt{2 \times 9.1 \times 10^{-31} \times 1.92 \times 10^{-17}}$
P = 5.91 x 10^-24 kg ms^-1
(b) Speed of an electron,
v = $\frac { p }{ m }$ = $\frac{5.91 \times 10^{-24}}{9.1 \times 10^{-31}}$ = 6.5 x 10⁶ kg ms^-1
(c) de-Broglie wavelength,
λ = $\frac { h }{ p }$ = $\frac{6.6 \times 10^{-34}}{5.91 \times 10^{-24}}$ = 1.117 x 10^-10 = 0.112 x 10^-9 m
λ = 0.112 nm

Question 7.
An electron and a photon each have a wavelength of 1 nm. Find, (a) their momenta (b) the energy of the photon, and (c) kinetic energy of electron.
Solution:
(a) Both electron and photon have same wavelength. so, they have same momentum also,
P = $\frac { h }{ λ }$ = $\frac{6.6 \times 10^{-34}}{1 \times 10^{-9}}$ = 6.6 x 10^-25 kg ms^-1
(b) Energy of a photon,
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-54
(c) Kinetic energy of electron,
K = $\frac {{ p }^{2}}{ 2m }$

K = 1.49 eV

Question 8.
Find the ratio of de-broglie wavelengths associated with two electron beams accelerated through 25 V and 36 V respectively.
Solution:
de-Broglie wavelength associate with potential difference λ ∝ $\frac { 1 }{ √V }$
$\frac {{ λ }_{1}}{ { λ }_{2} }$ = $\sqrt { \frac { { V }_{ 2 } }{ { V }_{ 1 } } } $ = $\sqrt { \frac { 36 }{ 25 } } $ = $\frac { 6 }{ 5 }$ ⇒ λ₁ : λ₂ = 6 : 5

Question 9.
A proton and an alpha particle, both initially at rest, are accelerated so as to have the same kinetic energy. What is the ratio of their de-Broglie wavelength?
Solution:
de-Broglie wavelength,
λ = $\frac { h }{ p }$ = $\frac { h }{ \sqrt { 2mK } } $
i.e.
λ ∝ $\frac { 1 }{ √m}$ [m_α = 4m_p]
$\frac {{ λ }_{p}}{ { λ }_{α} }$ = $\sqrt { \frac { { m }_{ α } }{ { m }_{ p } } } $ = $\sqrt { \frac { { 4m }_{ p } }{ { m }_{ p } } } $ = $\sqrt { \frac { 4 }{ 1 } } $ = $\frac { 2 }{ 1 }$
λ_p : λ_α = 2: 1

Question 10.
Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Find the ratio of maximum speeds of emitted electrons.
Solution:
Samacheer Kalvi 12th Physics Solutions Chapter 7 Dual Nature of Radiation and Matter-56

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