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An electric appliance is connected across the live wire (phase wire) and the neutral wire.

Observations :

1. When the key is plugged, the galvanometer shows a momentary deflection. When the current in coil 1 becomes steady, the galvanometer shows zero deflection, i.e., its pointer returns to the zero mark at the centre of the scale.

2. When the key is unplugged, the galvanometer shows a momentary deflection in the opposite direction relative to that in part (1) of the experiment. When the current in coil 1 becomes zero as the circuit is broken on unplugging the key, the galvanometer shows zero deflection, i.e., its pointer returns to the zero mark at the centre of the scale.

Conclusions:

As the current in coil 1 changes, the magnetic field associated with the current changes. This induces an electric potential difference in coil 2 which gives rise to an electric current and hence the deflection of the galvanometer. The direction of the induced current and hence that of the deflection of the pointer in the galvanometer depends on whether the current through coil 1 increases or decreases with time.

When there is a steady current in coil 1, there is no change in the associated magnetic field and hence no production of induced potential difference in coil

2. In that case there is no current in coil 2 and hence the galvanometer shows zero deflection.

[Note : Coil 1 is called the primary coil while coil 2 is called the secondary coil. This is because when the current through coil 1 is changed, induced current appears in coil 2.]

1. The intensity of light emitted by the filament of a bulb depends on the temperature of the filament. It increases with the temperature.

2. The melting point of the material used to make the filament of a bulb should be very high so that the filament can be heated to a high temperature by passing a current through it, without melting it. This enables us to obtain more light. The melting point of tungsten is very high.

Hence, tungsten is used to make a solenoid type coil (filament) in an electric bulb.

1. Copper and aluminium are good conductors of electricity.

2. Copper, and aluminium have very low resistivity. Hence, when an electric current flows through a wire of copper or aluminium, heat produced is comparatively low. Therefore, for electric power transmission, copper or aluminium wire is used.

(a) Given diagram shows the construction of an electric motor.

(b) An electric motor works on the principle that a current-carrying conductor placed in a magnetic field experiences a force. In this case, the forces acting on different parts of the coil of the motor produce the rotational motion of the coil.

(c) The rotation of the coil is based on Fleming’s left hand rule.

(d) Fleming’s left hand rule: The left hand thumb, index finger, and the middle finger are stretched so as to be perpendicular to each other. If the index finger is in the direction of the magnetic field, and the middle finger points in the direction of the current, then the direction of the thumb in the direction of the force on the conductor.

(e) Uses / applications of an electric motor: 

(1) In domestic appliances such as a mixer, a blender, a refrigerator and washing machine. 

(2) In an electric fan, a hair dryer, a record player, a tape recorder and a blower. 

(3) In an electric car, a rolling mill, an electric crane, an electric lift, a pump, a computer and an electric train.

Data : P₁ = 500 W, t₁ = 30 min = \(\frac{30}{60}\) h

= \(\frac{1}{2}\) h, P₂ = 600 W, t₂ = 20 min = \(\frac{20}{60}\) h = \(\frac{1}{3}\) h

Electrical energy used = Pt

TV set : P₁t₁ = 500 W × \(\frac{1}{2}\) h = 250 W·h

Heater : P₂t₂ = 600 W × \(\frac{1}{3}\) h = 200 W·h

Thus, the TV set will spend more electrical energy than the heater.

1. The working of heating devices such as a toaster and an electric iron is based on the heating effect of electric current, i.e., conversion of electric energy into heat by passage of electric current through a metallic conductor.

2. An alloy, such as Nichrome, has high resistivity and it can be heated to a high temperature without oxidation, in contrast to pure metals. Therefore, the coils in heating devices such as a toaster and an electric iron are made of an alloy, such as Nichrome, rather than a pure metal.

Observations:

The two deflections, in parts (1) and (2) of the experiment, are in the opposite directions.

(3) If instead of the magnet, the coil is moved towards the stationary magnet, the deflection of the pointer in the galvanometer is observed in one direction, while if the coil is moved away from the magnet, the deflection is observed in the opposite direction. The effect of moving the north pole of the magnet towards the coil and the effect of moving the coil towards the north pole of the magnet are the same.

(4) If both the coil and the magnet are kept stationary, no deflection is observed.

(5) The two deflections are in opposite directions.

(6) Whenever there is relative motion of the coil and the magnet, electric potential difference is induced in the circuit which gives rise to, i.e., induces, an electric current in the circuit causing the deflection of the pointer in the galvanometer. The direction of the current and hence that of the deflection of the pointer in the galvanometer depends on which pole of the magnet faces the coil as well as the direction of relative motion.

[Note: If the velocity of the magnet is increased, the induced current increases, and hence the deflection of the pointer in the galvanometer increases.]

Galvanometer is a sensitive device used to detect the presence of current in a circuit as well as to determine the direction of the current in the circuit.

With suitable modification, it can be used to measure charge, current and voltage. Its working is based on the same principle as that of an electric motor. Here, a coil is pivoted (or suspended) between the pole pieces of a magnet and a pointer is connected to the coil. As the coil rotates when a current is passed through it, the pointer also rotates. The rotation of the coil and hence the deflection of the coil is proportional to the current. The pointer deflects on both sides of the Central zero mark depending on’ the direction of the current.

(d) A system where persons buy and sell goods directly or indirectly

(b) Adam Smith

(b) Want – satisfying capacity of goods and services

(c) Quantity demanded equals quantity supplied

(i – c), 

(ii – d), 

(iii – a), 

(iv – f).

(b) Adam smith

(i – b),

(ii – d), 

(iii – e), 

(iv – f).

1. False    

2. True 

3. True 

4. True           

5. False   

6. False 

7. True 

8. False            

9. True    

10. True 

11. True 

12. False           

13. False    

14. True  

Prof.Ragner Frisch, the Nobel Prize winner in Economics (1920), coined the words Micro and Macro Economics for the first time.

1. Negative feedback is used in an amplifier.

2. Positive feedback is used in an oscillator.

Micro economics is the study of the economic actions of individuals and small groups of individuals. According to Boulding, “It is the study of particular firms, particular households, individual prices, wages, income, individual industries, particular commodities”.

It is the process of reasoning from a part to the whole, from particular to general or from individual to the universal.

1. It helps in allocation of resources. 

2. Provides solution to the problem of choice. 

3. Helps in formulating various.economic policies. 

4. Explains determination of the price. 

5. Helps to know the working of an economy

Economic theories are statements of economic tendencies of people. While developing economic theories, the Economists formulate assumptions. So, economic theory derives generalizations of economic facts through two methods: 

They are as follows:

Deductive Method: This method was developed by David Recardo, J.S.Mill, T.R.Malthus, Alfred Marshall and others. This method is also called as Analytical method.

Under this method, the conclusions are drawn from the universal to the individual or from general to the particular. This method derives new conclusions from assumptions. It is also called as ‘Scientific Method’. It includes four stages viz.,

• Identification of the hypothesis to be tested. 
• Generations of predictions from the hypothesis. 
• Conducting experiments to check whether the predictions are correct. 
• Confirming the hypothesis.

Inductive Method: This method was advocated by Frederic List, Rosher and Hilde Brand. Inductive method is a process of reasoning from particular to general or from individual to the universal. It functions in four stages viz.,

• Selection of an economic problem and defining the same clearly
• Collection of data using statistical techniques. 
•  Analysing the data. 
• Observation and generalization to establish a general truth. 

The inductive method is also called as historical method or concrete method and realistic method. In this method, we investigate particular facts or historical events and try to generalize the findings of the observation for the entire economic system.

It is concluded that both Deductive and inductive methods are ential for the proper development of economic laws. According to Alfred Marshall, “Induction and deduction are both needed for scientific thought just as the right and left foot are both needed for walking”.

The examples for Capitalistic or Market Economy are USA, Japan, Australia, UK etc.

Feedback is the process of taking a part of output signal and feeding it back to input circuit.

Feedback factor is the ratio of feedback voltage to output voltage.

Closed loop gain is the gain of an amplifier with negative feedback.

Positive feedback is seldom used in amplifiers because the positive feedback increases distortion and noise, decreases the gain stability and results in poor frequency response.

(i) Positive feedback.

(ii) Negative feedback.

Negative feedback.

The product of open loop gain and feedback ratio is called the loop gain.

Bandwidth increases.

(i) Poor gain stability

(ii) More distortion and noise

(iii) Poor frequency response.

Positive feedback is applying the feedback signal in phase with applied input.

With positive feedback, gain of an amplifier increases and with negative feedback, gain an amplifier decreases.

1. It has unrealistic assumptions. 

2. It is based on unrealistic analysis. 

3. Narrow in scope.

Micro Economics is the study of the economic actions of individuals and small groups of . individuals. According to Boulding, “The study of particular firm, particular household, individual price, wage, income, individual industry, particular commodity, is Micro Economics.”

Micro Economics is an important method of economic analysis. It has both theoretical and practical importance:

(a) Helpful in the efficient employment of resources-allocation of resources: Micro Economics deals with the economizing of scarce resources with efficiency. The principal problem faced by modern Governments is the allocation of resources among competing wants. In this sense, Micro Economics is used by the Government in the efficient employment of resources and achieving economic growth With stability.

(b) Helps in understanding the working of the economy: Micro Economics is of utmost importance in understanding the working of a free economy. In such an economy, there is no agency to plan and coordinate the working of the economic system. The decisions like how to produce, what do produce etc., are taken by producers mid consumers without any outside influence.

(c) Provide tools for economic policies: Micro economics provides analytical tools for evaluating the economic policies of an Economy. Price mechanism or market mechanism is the tool which helps us in this respect. Micro Economics thus helps in formulating correct price policies.

(d) Useful in understanding the problems of Taxation: The study of micro economics helps in understanding some of the problems of taxation. It is used to explain the welfare implications of a tax. It studies the distribution of incidence of a commodity tax (excise duty/sales tax) between sellers and consumers.

(e) Helpful in International Trade: In the field of international trade, it is used to explain the gains from international trade, balance of payments and the determination of the foreign exchange rate.

(f) Helps us to know Market structure: The study of Micro Economics is useful in understanding the different market conditions like perfect competitive market, monopoly, duopoly, oligopoly etc.

(g) Construction and use of economic models: Micro Economics constructs and uses simple models for understanding the actual economic phenomena. It helps not only to describe the actual economic situation, but also suggests policies that would bring in the desired results;

(h) The basis of predictions: Micro Economic theory can be used as the basis for prediction. This does not mean that it will enable us to predict the future. It will enable the user to make conditional predictions.

(i) Solution to the problem of choice: The study of Micro Economics helps to find solution to the problem of choice by providing various guidelines for proper allocation of scarce resources.

(j) Helps business executives: Micro Economics helps the business executives in the attainment of maximum productivity with existing resources. It is with its help that one is able to know the consumer demands and calculate the cost of production.

(k) Helps in formulation of economic planning: In order to solve the basic problems of an economy, conscious planning is required. The knowledge of micro economics helps the members of National Planning Commission to frame aims and objectives based on the availability of resources.

(l) Expands intellectual capacity of Human mind:- The study of economics helps individuals to develop their thinking and intelligence to take appropriate decisions in their daily life.

(m) To examine the conditions of economic welfare: Micro Economics can be used to examine the conditions of economic welfare. Welfare economics is related to maximization of social welfare. The study of Micro Economics may be the greatest help in raising the standard of living of the population.

(n) Helps different sections of the society: The knowledge of Micro Economics is very important to know the different sections of the society like poor, middle class, rich, male and female population, skilled and unskilled labourers etc. It helps us to understand the problems of these sections and to arrive at proper Solutions. Thus, Micro Economics is considered as an efficient method of problem solving.

Negative feedback is applying the feedback signal 180° out of phase with the applied input.

With negative feedback, gain decreases.

Stability increases.

The Centrally planned or Socialistic economies are North Korea, Cuba, Russia, China and Vietnam.

A Planned economy, also called as Socialistic economy is that economy where the economic activities are controlled by the central Government. Here, the Government takes decisions about the allocation of resources in accordance with objectives to attain economic and social welfare. Example, Russia, China, North Korea etc.

A Market Economy also known as Capitalistic Economy is that economy in which the economic decisions are undertaken on the basis of market mechanism by the private entrepreneurs. It functions on demand and supply conditions. In USA, Japan, Australia, UK and other countries we can see Market Economic systems.

In market economy, private individuals own the factors of production. Here, profit is the sole motive. There is least intervention by the Government.

Price mechanism plays a major role in market economy. It is a balancing wheel of the market mechanism. Prices coordinate decisions of the producers and consumers. The price is determined by demand and supply in the market. No individual organization or Government is responsible for the production and distribution or pricing of goods. All depend on market mechanism).

Regarding the basic problems of an economy, the problem of “What to produce”, is solved on the basis of demand and profit. The producers produce those products which bring more income.

The problem of “How the goods are to be produced”, is determined by the competition among different entrepreneurs. They select the least cost combination of technology so that they can get more returns with less cost.

In Market Economy, the/problem of “For whom to produce”, is decided on the basis of purchasing power of consumers. The producers produce commodities for the rich as they can afford to pay more but poorer sections of the society get neglected.

In Market Economy, profits and losses play a predominant role in growth and development of every producer.

Micro Economics is the study of the economic actions of individuals and small groups of individuals. According to Boulding, “ It is the study of particular firms, particular households, individual prices, wages, income, individual industries, particular commodities”.

The major limitations of Micro Economics are as follows: 

(a) Assumptions are unrealistic: The study of Micro-Economics assumes that ‘other tilings being constant’, which is not realistic. In fact, all factors are subject to change and not constant.

(b) Micro Economics is an unrealistic analysis: Micro-Economics uses static analysis. The conclusions drawn from Micro Economic analysis are not valid. For example, individual savings is good since it promotes individual economic prosperity. But if many people indulge in savings, it may lead to a fall in demand leading to less investment and causing unemployment.

(c) The assumption of full employment is incorrect: The microeconomics is based on the assumption of full employment i.e., all the resources are completely employed in production process, which is just imaginary and not correct.

(d) Laissez-faire policy (Minimum intervention of Government): The assumption of laissez faire policy is not practical in real world, where we see intervention of Government in economic activities.

(e) Ignores Macro economic analysis: The knowledge of an entire economy is very essential to the people as it includes all the economic elements. But the micro economics concentrates only on a small part of the whole economy.

(f) It is limited in scope: The scope of micro economics is limited and narrow. It does not include income theory, inflation, monetary policies etc. which are very important for economic analysis.

The main types of economic system are: 

1. Socialistic/Centrally Planned Economy 

2. Capitalistic/Market Economy and. 

3. Mixed Economy. 

1. Centrally Planned Economy or Socialistic Economy: A planned economy also called as socialistic.economy is that economy where the economic activities are controlled by the central Government. Here, the Government takes decisions about the allocation of resources in accordance with objectives to attain economic and social welfare. Example, Russia, China, North Korea etc. Here, the basic economic problems are solved as follows:

Government takes decisions about the allocation of resources in accordance with the predetermined goals and objectives to attain maximum social welfare. Government decides what to produce, how to produce and what prices are to be fixed.

• Regarding what to produce, the Government may produce those goods and services which are most useful for its society. 
• Regarding how to produce, the most suitable technique in production is adopted whether labour intensive or capital intensive in accordance with the situation in the economy. 
• Regarding for whom to produce, the goods and services are produced with the welfare of people who are suffering from hunger in mind even though there may be a loss.
•  It gives importance to the quality of life rather than quantity of production. 
• It focuses the resources on rapid economic development.

2. Market Economy: A Market Economy also known as Capitalistic Economy is that economy in which the economic decisions are undertaken on the basis of market mechanism by the private entrepreneurs. It functions on demand and supply conditions. In USA, Japan, Australia, UK and other countries we can see Market Economic systems.

In Market Economy, private individuals own the factors of production. Here, the profit is the main goal of business. There is the least intervention of Government.

Price mechanism plays a major role in Market Economy. It is a balancing wheel of the market mechanism. Prices coordinate decisions of the producers and consumers. The price is determined by demand and supply in the market. No individual organization or Government is responsible for the production and distribution or pricing of goods. All depend on market mechanism.

Regarding basic problems of an economy, the problem of what to produce is solved on the basis of demand and profit. The producers produce those products which bring more income.

The problem of how the goods are to be produced is determined by the competition among different entrepreneurs. They select least cost effective combination of technologies so that they can get more returns for their investment.

In Market Economy, the problem of for whom to produce is decided on the basis of the purchasing power of the consumers. The producers produce commodities for the rich who can afford to pay more but poorer sections of the society are neglected.

In Market Economy, profits and losses play a predominant role in the growth and development of every producer.

3. Mixed Economy: A mixed economy is that economy in which we can see coexistence of both private and public sector enterprises. It is the combination of Socialistic and Capitalistic features. The best example is India.

In a mixed economic system, the resources are owned by both the Government and Private individuals. Here, some areas of economic activities are totally governed by the Government and other sectors are open to the private sector.

The Government involves in those activities which promote maximum social and economic welfare without any profit motive. The Private sector functions with the intention of maximizing profits. Here we find dual pricing system. For example, the supply of rice through Government Fair Price shops is low when compared to the private provision stores.

In this type of economy, the Government takes the responsibility to run certain essential sectors like Railways, Printing of currency notes, Atomic energy, public parks etc. Here, the basic problems are solved both by Public and Private Sectors.

Regarding what to produce, consumers play the main role. But, the Government also interferes by imposing tax or giving subsidy. The problem of how to produce, the private sector will decide the best cost effective technology to maximize profits and public sector will select the technology on the basis of composition of resources. The problem of for whom to produce depends on both the purchasing’power of the consumers and the Government policy towards weaker sections of the society.

A Market economy also known as Capitalistic economy is that economy in which the economic decisions are undertaken on the basis of market mechanism by the private entrepreneurs It functions on demand and supply conditions. Example, USA.

A Mixed Economy is that economy in which we can see coexistence of both private and public sector enterprises. It is the combination of Socialistic and Capitalistic features. The best example for this is India.

In a Mixed Economic system, the resources are owned by both the Government and Private individuals. Here, some areas of economic activities are totally governed by the Government and other sectors are open to the private sector also.

The Government involves in those activities which promote maximum social and economic welfare without any profit motive. The Private sector functions with the intention of maximizing profits. Here we find dual pricing system. For example, the supply of Rice through Government Fair Price shojis is low when compared to the private provision stores.

In this type of economy, the Government takes the responsibility to run certain essential sectors like Railways, Printing of currency notes, Atomic energy, public parks etc. Here, the basic problems are solved both by Public and Private Sectors.

Regarding what to produce,-consumers play a main role. But, the Government also interferes by imposing tax or giving subsidy. The problem of how to produce, the private sector will follow the least cost effective technology to maximize profit and public sector will select , the technology on the basis of composition of resources. The problem of for whom to produce depends on both the purchasing power of consumers and the Government policy towards weaker sections of society.

Input impedance increases.

Positive feedback.

Voltage shunt negative feedback.