अर्थशास्त्र Economics

Quick summary

Economics is the study of how people, firms and governments use scarce resources to satisfy unlimited wants. This topic covers the main definitions of economics (Adam Smith, Marshall, Robbins, Samuelson), the basic economic problem, and the difference between micro and macro economics.

Key points

• The word economics comes from the Greek word oikonomia, meaning management of the household.
• Adam Smith (1776, The Wealth of Nations) gave the wealth definition: economics is the science of wealth. He is called the Father of Economics.
• Alfred Marshall (1890, Principles of Economics) gave the welfare definition: economics studies mankind in the ordinary business of life — how people earn and use income to get material welfare.
• Lionel Robbins (1932) gave the scarcity definition: economics studies human behaviour as a relationship between ends (wants) and scarce means which have alternative uses.
• Paul Samuelson gave the growth definition: economics studies how society chooses to use scarce resources to produce goods over time and distribute them for present and future consumption.
• The central problem of every economy is choice, because wants are unlimited and resources are limited. The three basic questions are: What to produce? How to produce? For whom to produce?
• Microeconomics studies individual units (a consumer, a firm, the price of one good). It is also called price theory.
• Macroeconomics studies the economy as a whole (national income, employment, general price level). It is also called income theory. The terms "micro" and "macro" were first used by Ragnar Frisch in 1933; macroeconomics became popular after Keynes (1936).
• Positive economics describes "what is"; normative economics says "what ought to be".
• Economics is both a science (it studies cause and effect) and an art (it helps solve practical problems).

Important terms

• Scarcity (टंचाई) – resources are limited compared to wants.
• Opportunity cost – the value of the next best alternative given up when a choice is made.
• Want – a desire for a good or service backed by the need to satisfy it.
• Economic good – a good that is scarce and has a price.
• Free good – a good available in plenty without a price, e.g. air.
• Production possibility curve (PPC) – a curve showing the different combinations of two goods an economy can produce with given resources and technology.

Key facts

• The PPC slopes downward from left to right and is concave to the origin, because of increasing opportunity cost.
• Opportunity cost along the PPC = units of good Y given up ÷ extra units of good X gained.

5 important questions

Q1. What is microeconomics?

Microeconomics studies the behaviour of individual economic units such as a consumer, a firm or an industry. It explains how the price of a single good is decided. It is also called price theory.

Q2. Define opportunity cost.

Opportunity cost is the benefit of the next best alternative that is given up when we make a choice. For example, if land is used to grow wheat, the rice that could have been grown is its opportunity cost.

Q3. Explain Robbins' scarcity definition of economics and its criticism.

• Definition: economics studies human behaviour as a relationship between ends and scarce means having alternative uses.
• Features: unlimited ends (wants); scarce means; alternative uses of means; need for choice.
• Merits: universal, scientific, applies to all economies.
• Criticism: ignores human welfare; treats economics as neutral between ends; does not explain growth of resources; ignores macro problems like unemployment (Keynes).

Q4. Distinguish between microeconomics and macroeconomics.

• Unit of study: individual units vs economy as a whole.
• Main tool: price mechanism (demand and supply) vs aggregate demand and aggregate supply.
• Other name: price theory vs income and employment theory.
• Examples: price of rice, a firm's output vs national income, inflation, unemployment.
• Both are interdependent; one cannot be fully understood without the other.

Q5. What is the central problem of an economy? Explain with the help of the PPC.

• Wants unlimited, resources scarce, so choice is needed.
• Three questions: what, how and for whom to produce.
• PPC shows combinations of two goods with full use of resources.
• A point on the curve = efficient use; inside the curve = unemployment of resources; outside = not possible now.
• Shift of PPC to the right = economic growth.

Exam tip

Learn the four definitions with the name, year and one-word label (wealth, welfare, scarcity, growth). Draw and label the PPC whenever you write about the central problem.

Quick summary

Every society must solve the same basic problems: what to produce, how to produce, for whom to produce, and how to grow. An economic system is the set of institutions through which a society answers these questions. The three main types are capitalism (market economy), socialism (command economy) and the mixed economy, which India follows.

Key points

• Central problems arise because resources are scarce and have alternative uses, while wants are unlimited.
• Capitalism (free-market economy): means of production are privately owned; decisions are guided by the price mechanism and the profit motive. Examples: USA, UK (largely).
• Features of capitalism: right to private property, freedom of enterprise, consumer sovereignty, competition, profit motive, inheritance, minimal state role (laissez-faire).
• Merits: efficiency, innovation, wide consumer choice, automatic working through prices. Demerits: inequality of income, monopolies, trade cycles and unemployment, neglect of public goods.
• Socialism (command economy): means of production owned and controlled by the state; decisions taken by a central planning authority. Examples: former USSR, Cuba.
• Features of socialism: social ownership, central planning, equality, absence of profit motive in key sectors, limited consumer choice.
• Merits: equality, full use of resources, no exploitation, social welfare. Demerits: bureaucracy, lack of incentive, inefficiency, loss of freedom, black markets.
• Mixed economy: public and private sectors exist side by side; prices work but the state regulates and plans. India chose this after 1950 (Industrial Policy 1948 and 1956).
• After 1991 India moved towards a more market-oriented mixed economy (LPG reforms).

Important terms

• Price mechanism – the free working of demand and supply that decides prices and resource allocation.
• Consumer sovereignty (उपभोक्ता सार्वभौमत्व) – consumers' choices decide what is produced.
• Laissez-faire – policy of non-interference by the state in economic matters.
• Central planning authority – a state body that takes all major economic decisions in a command economy.
• Public sector – enterprises owned and managed by the government.
• Private sector – enterprises owned by individuals or companies for profit.

Key facts

5 important questions

Q1. What are the central problems of an economy?

What to produce and in what quantity, how to produce (which technique), for whom to produce (distribution), and how to ensure full use and growth of resources.

Q2. Define consumer sovereignty.

It means the consumer is "king": what goods are produced and in what quantity is decided by consumers' demand in the market.

Q3. Explain the features, merits and demerits of capitalism.

Outline: meaning; features (private property, freedom of enterprise, price mechanism, competition, profit motive, consumer sovereignty, laissez-faire); merits (efficiency, growth, innovation, choice); demerits (inequality, monopoly, cyclical unemployment, waste in advertising, neglect of the poor); conclusion – pure capitalism rarely exists today.

Q4. What is socialism? Discuss its merits and limitations.

Outline: meaning and examples; features (state ownership, central planning, equality, no exploitation); merits (equality, planned growth, social security, full employment); limitations (bureaucracy, lack of incentives, inefficiency, loss of freedom, wrong pricing); collapse of the USSR in 1991.

Q5. Explain the mixed economy with special reference to India.

Outline: meaning; features (co-existence of public and private sectors, planning, regulation, welfare goals, price mechanism); India's case – Industrial Policy 1948 and 1956, Five-Year Plans, public sector in heavy industry; changes after 1991 (liberalisation, privatisation); merits and problems (inefficient PSUs, red tape); conclusion.

Exam tip

Draw the three-column comparison table in long answers – it earns marks quickly and shows clear understanding.

Quick summary

Demand means the quantity of a good that consumers are willing and able to buy at a given price during a given time. This topic covers the determinants of demand, the law of demand, its exceptions, and the difference between movement along and shift of the demand curve.

Key points

• Demand needs three things: desire, ability to pay (purchasing power) and willingness to pay. Demand is always stated with a price and a time period.
• Demand function: Dx = f(Px, Py, Y, T, E...) – demand for good x depends on its own price, prices of related goods, income, tastes and expectations.
• Law of demand (stated by Marshall): other things remaining the same, when the price of a good falls, its quantity demanded rises, and when the price rises, quantity demanded falls. Price and demand are inversely related.
• Assumptions (ceteris paribus): income, tastes, prices of related goods, population and expectations remain constant.
• The demand curve slopes downward from left to right.
• Reasons for downward slope: law of diminishing marginal utility, income effect, substitution effect, new buyers entering at lower price, multiple uses of a good.
• Exceptions: Giffen goods (inferior goods like coarse grain for the very poor), Veblen or prestige goods (diamonds), expectation of future price change, ignorance of quality, emergencies such as war or famine.
• Movement along the curve (extension or contraction of demand) happens only due to a change in the good's own price.
• Shift of the curve (increase or decrease in demand) happens due to change in other factors like income or tastes. A rightward shift means increase; a leftward shift means decrease.
• Market demand is the horizontal sum of individual demands at each price.

Important terms

• Demand schedule – a table showing quantities demanded at different prices.
• Normal good – demand rises when income rises.
• Inferior good – demand falls when income rises.
• Substitutes – goods used in place of each other, e.g. tea and coffee.
• Complements – goods used together, e.g. car and petrol.
• Giffen paradox – for a Giffen good, a fall in price reduces demand (named after Sir Robert Giffen).
• Veblen effect – status goods are demanded more at higher prices (Thorstein Veblen).

Key facts

• Law of demand: P ↑ → Qd ↓ and P ↓ → Qd ↑ (inverse relation).
• Price of substitute ↑ → demand for good ↑ (curve shifts right).
• Price of complement ↑ → demand for good ↓ (curve shifts left).
• Income ↑ → demand for normal good ↑, for inferior good ↓.

5 important questions

Q1. State the law of demand.

Other things remaining constant, the quantity demanded of a good rises when its price falls and falls when its price rises. There is an inverse relation between price and quantity demanded.

Q2. What is a Giffen good?

A Giffen good is an inferior good on which poor people spend a large part of their income, e.g. coarse grain. When its price falls, they buy less of it and more of better food. So the law of demand does not apply.

Q3. Explain the law of demand with its assumptions and exceptions.

• Statement of the law; schedule and downward-sloping curve.
• Assumptions: constant income, tastes, prices of related goods, population, no expected price change.
• Exceptions: Giffen goods, prestige goods, speculation, ignorance, emergencies, necessities.
• Conclusion: law is qualitative, not quantitative.

Q4. Why does the demand curve slope downward?

• Diminishing marginal utility: buyer buys more only at lower price.
• Income effect: lower price raises real income.
• Substitution effect: good becomes cheaper than substitutes.
• New consumers enter the market.
• Different uses: cheaper good is put to more uses (e.g. electricity).

Q5. Distinguish between change in quantity demanded and change in demand.

• Cause: own price vs other factors (income, tastes, related prices).
• Diagram: movement along same curve vs shift of whole curve.
• Names: extension/contraction vs increase/decrease.
• Example: fall in price of mangoes vs rise in income of buyers.

Exam tip

Always write "other things remaining the same" when stating the law. In diagrams, label axes clearly: price on the Y-axis, quantity on the X-axis.

Quick summary

Elasticity of demand measures how much the quantity demanded responds to a change in price, income or the price of a related good. Marshall developed the idea of price elasticity. This topic covers its types, degrees, methods of measurement and the factors that affect it.

Key points

• Price elasticity of demand (Ep) = percentage change in quantity demanded ÷ percentage change in price. The minus sign is usually ignored because price and demand move in opposite directions.
• Perfectly elastic (Ep = ∞) – horizontal demand curve.
• Relatively elastic (Ep > 1) – flatter curve; luxuries.
• Unitary elastic (Ep = 1) – rectangular hyperbola.
• Relatively inelastic (Ep < 1) – steeper curve; necessities.
• Perfectly inelastic (Ep = 0) – vertical demand curve.
• Five degrees of price elasticity:
• Income elasticity is positive for normal goods, negative for inferior goods.
• Cross elasticity is positive for substitutes and negative for complements.
• Methods of measurement: percentage (proportionate) method, total outlay (expenditure) method, point (geometric) method and arc method.
• Total outlay method (Marshall): if price falls and total expenditure rises, Ep > 1; if expenditure stays same, Ep = 1; if expenditure falls, Ep < 1.
• Factors affecting elasticity: nature of the good (necessity or luxury), availability of substitutes, number of uses, share of income spent, postponement of use, habits, time period, price level.
• Uses: pricing decisions by firms and monopolists, taxation policy by government, price discrimination, international trade, wage fixing.

Important terms

• Elasticity (लवचिकता) – degree of responsiveness of demand.
• Point elasticity – elasticity at a point on a straight-line demand curve = lower segment ÷ upper segment.
• Arc elasticity – elasticity between two points on a curve, using average price and average quantity.
• Total outlay – price × quantity bought.

Formulas

• Ep = (ΔQ/Q) ÷ (ΔP/P) = (ΔQ/ΔP) × (P/Q)
• Arc elasticity = [ΔQ / (Q₁ + Q₂)] ÷ [ΔP / (P₁ + P₂)]
• Point elasticity (straight-line curve) = lower segment ÷ upper segment
• Income elasticity Ey = (ΔQ/Q) ÷ (ΔY/Y)
• Cross elasticity Exy = (ΔQx/Qx) ÷ (ΔPy/Py)

Here Q = quantity, P = price, Y = income, Δ = change.

5 important questions

Q1. Define price elasticity of demand.

It is the ratio of the percentage change in quantity demanded to the percentage change in price. It shows how sensitive buyers are to a price change.

Q2. Price of a pen falls from Rs. 10 to Rs. 8 and demand rises from 100 to 150 pens. Find Ep.

• ΔQ = 150 − 100 = 50; ΔP = 10 − 8 = 2 (fall).
• Ep = (ΔQ/ΔP) × (P/Q) = (50/2) × (10/100) = 25 × 0.1 = 2.5.
• Ep > 1, so demand is relatively elastic.

Q3. Explain the degrees of price elasticity of demand with diagrams.

• Perfectly elastic: horizontal line parallel to X-axis.
• Perfectly inelastic: vertical line parallel to Y-axis.
• Unitary: rectangular hyperbola; total outlay constant.
• Relatively elastic: flatter curve; small price change, big demand change.
• Relatively inelastic: steeper curve; big price change, small demand change.
• Give one example of each (salt for inelastic, AC for elastic).

Q4. Explain the total outlay method with an example.

• Compare total expenditure before and after price change.
• Price falls from Rs. 5 to Rs. 4, quantity rises from 10 to 15: outlay rises from 50 to 60, so Ep > 1.
• If outlay remains 50, Ep = 1; if it falls, Ep < 1.
• Limitation: tells only whether Ep is more, equal or less than 1, not the exact value.

Q5. What factors determine the elasticity of demand?

• Necessities inelastic, luxuries elastic.
• More substitutes → more elastic.
• Goods with many uses → elastic.
• Small share of budget (salt, matchbox) → inelastic.
• Use can be postponed → elastic.
• Habit-forming goods → inelastic.
• Long run → more elastic than short run.

Exam tip

In numerical questions, write the formula first, then substitute values, then state the type of elasticity. Examiners give marks for each step.

Quick summary

Supply is the quantity of a good that sellers are willing and able to offer for sale at a given price during a given time. The law of supply says that, other things remaining the same, quantity supplied rises when price rises and falls when price falls. Elasticity of supply measures how strongly quantity supplied responds to a change in price.

Key points

• Supply differs from stock: stock is the total quantity available; supply is the part actually offered at a price.
• Determinants of supply: price of the good, cost of production (input prices), technology, prices of related goods, goals of the firm, government policy (taxes and subsidies), number of sellers, expectations, natural factors (for farm goods).
• Law of supply: price and quantity supplied move in the same direction (direct relation), ceteris paribus. The supply curve slopes upward from left to right.
• Reasons: higher price means higher profit; new firms enter; firms can cover rising marginal cost.
• Exceptions: backward-bending supply of labour, perishable goods in distress sale, expected fall in price, rare goods (paintings) whose supply is fixed, agricultural goods in the short run.
• Movement along the curve (extension/contraction) – caused only by change in own price.
• Shift of the curve (increase/decrease) – caused by change in other factors, e.g. better technology shifts supply to the right.
• Elasticity of supply (Es) = % change in quantity supplied ÷ % change in price.
• Five degrees: perfectly elastic (Es = ∞), relatively elastic (Es > 1), unitary (Es = 1), relatively inelastic (Es < 1), perfectly inelastic (Es = 0).
• Factors affecting Es: time period (supply is more elastic in the long run), nature of the good (perishable vs durable), cost behaviour, availability of spare capacity, storage facilities.

Important terms

• Supply schedule – a table showing quantities supplied at different prices.
• Extension of supply (पुरवठ्याचा विस्तार) – more supplied because price rose.
• Contraction of supply – less supplied because price fell.
• Increase in supply – more supplied at the same price (rightward shift).
• Market period – a very short time in which supply is fixed (Es = 0).

Formulas

• Es = (ΔQ/Q) ÷ (ΔP/P) = (ΔQ/ΔP) × (P/Q)
• A straight-line supply curve through the origin has Es = 1; one that cuts the price axis has Es > 1; one that cuts the quantity axis has Es < 1.

Worked example: price rises from ₹10 to ₹12, quantity supplied rises from 100 to 130 units.
ΔQ/Q = 30/100 = 0.30; ΔP/P = 2/10 = 0.20; Es = 0.30 ÷ 0.20 = 1.5 (relatively elastic).

5 important questions

Q1. State the law of supply.

Other things remaining constant, the quantity supplied of a good increases with a rise in its price and decreases with a fall in its price.

Q2. Distinguish between extension and increase in supply.

Extension is a movement along the same supply curve due to a rise in the good's own price. Increase is a rightward shift of the whole curve due to factors other than price, such as better technology.

Q3. Explain the law of supply with a schedule and diagram. State its assumptions and exceptions.

Outline: statement; schedule (e.g. ₹10–100 units, ₹12–130, ₹14–160); upward-sloping curve; assumptions (no change in cost, technology, taxes, related prices); reasons; exceptions (labour supply, perishable goods, expected price fall, rare goods).

Q4. What is elasticity of supply? Explain its types with diagrams.

Outline: definition and formula; five degrees with a diagram for each; geometric rule (where the line meets the axes); a numerical example.

Q5. Discuss the determinants of supply and the factors affecting elasticity of supply.

Outline: list and explain cost, technology, related prices, taxes/subsidies, number of firms, expectations, nature; then time period (Marshall's market period, short run, long run), nature of goods, spare capacity, storage.

Exam tip

Always write ceteris paribus (other things being equal) in the statement of the law, and label axes as Price (Y) and Quantity supplied (X).

Quick summary

In a competitive market the price of a good is set by the interaction of demand and supply. Equilibrium is reached where quantity demanded equals quantity supplied. This topic explains how the equilibrium price is found, what happens when demand or supply changes, the role of time (Marshall), and price controls such as price ceilings and floors.

Key points

• Market equilibrium: the point where the demand curve and supply curve intersect; Qd = Qs.
• At a price above equilibrium there is excess supply (surplus); sellers cut prices until the surplus disappears.
• At a price below equilibrium there is excess demand (shortage); buyers bid up the price.
• Marshall's scissors: both demand (utility) and supply (cost) decide price, like the two blades of a pair of scissors.
• Increase in demand (supply same) → price rises, quantity rises.
• Decrease in demand → price falls, quantity falls.
• Increase in supply (demand same) → price falls, quantity rises.
• Decrease in supply → price rises, quantity falls.
• Both increase equally → quantity rises, price unchanged.
• Effect of shifts:
• Time element (Marshall): in the market period demand dominates price; in the long run cost of production (supply) dominates.
• Price ceiling (maximum price): fixed below equilibrium to protect consumers (e.g. ration shop prices); causes shortage, queues, black market.
• Price floor (minimum support price): fixed above equilibrium to protect producers (e.g. MSP for wheat and paddy); causes surplus that the government must buy and store.
• Stable equilibrium: after a disturbance the market returns to equilibrium.

Important terms

• Equilibrium price (समतोल किंमत) – the price at which demand equals supply.
• Equilibrium quantity – the quantity bought and sold at that price.
• Excess demand – Qd > Qs at a given price.
• Excess supply – Qs > Qd at a given price.
• Market period – very short period when supply cannot change.

Formulas

• Equilibrium condition: Qd = Qs
• Linear example: Qd = 100 − 5P and Qs = 20 + 3P. 100 − 5P = 20 + 3P → 80 = 8P → P = ₹10; Q = 100 − 50 = 50 units (check: 20 + 30 = 50).

5 important questions

Q1. What is equilibrium price?

It is the price at which the quantity demanded of a good equals the quantity supplied, so there is no tendency for the price to change.

Q2. What is a price ceiling? Give one effect.

A legal maximum price fixed below the equilibrium price. It creates a shortage, which can lead to rationing and black markets.

Q3. Explain the determination of equilibrium price with a schedule and diagram.

Outline: meaning; demand and supply schedule (as in the table); diagram with D and S crossing at E; surplus above and shortage below; how the market moves back to E; Marshall's scissors.

Q4. Explain the effects of changes in demand and supply on equilibrium price.

Outline: four basic cases with diagrams; simultaneous changes (equal, demand > supply, supply > demand); real examples (onion prices after poor rains).

Q5. Discuss the role of the time element in price determination according to Marshall.

Outline: market period (fixed supply, demand decides price), short period (supply changes through variable factors), long period (all factors variable; price = cost of production), secular period; diagram for each; conclusion.

Exam tip

In numerical questions, always check your answer by putting P back into both equations – it shows the examiner your answer is correct.

Quick summary

Utility analysis (also called the cardinal approach) explains consumer behaviour by assuming that satisfaction can be measured in numbers called utils. It was developed mainly by Alfred Marshall. This topic covers total and marginal utility, the law of diminishing marginal utility, the law of equi-marginal utility and consumer's surplus.

Key points

• Utility (उपयोगिता) is the want-satisfying power of a good. It is subjective, relative and ethically neutral (a harmful good like a cigarette also has utility for a smoker).
• Total utility (TU) is the total satisfaction from all units consumed. Marginal utility (MU) is the addition to TU from one more unit.
• Law of diminishing marginal utility (stated by Gossen, popularised by Marshall): as a person consumes more units of a good continuously, the MU from each extra unit goes on falling.
• Relation of TU and MU: when MU is positive, TU rises; when MU is zero, TU is maximum; when MU is negative, TU falls.
• Assumptions of the law: units are standard and homogeneous, consumption is continuous (no time gap), consumer is rational, tastes and income do not change, utility is measurable.
• Exceptions/limitations: hobbies (stamps, coins), money (debated), music and poetry, misers, rare collections; the law fails if units are too small.
• Law of equi-marginal utility (Gossen's second law, law of substitution): a consumer gets maximum satisfaction when he spends his income so that the marginal utility of the last rupee spent on each good is equal.
• Consumer equilibrium for one good: MUx = Px (MU in money terms equals price).
• Consumer's surplus (Marshall): the difference between what a consumer is ready to pay and what he actually pays.
• Criticism of the cardinal approach: utility cannot be measured in numbers; MU of money is not constant; ignores income and substitution effects. Hicks and Allen replaced it with the ordinal (indifference curve) approach.

Important terms

• Util – an imaginary unit to measure utility.
• Cardinal utility – utility measured in numbers (1, 2, 3).
• Ordinal utility – utility only ranked (first, second).
• Rational consumer – one who aims at maximum satisfaction from his income.

Formulas

• MUn = TUn − TU(n−1)
• TU = ΣMU (sum of marginal utilities)
• Equi-marginal condition: MUx/Px = MUy/Py = ... = MU of money
• Consumer's surplus = potential price (what one is willing to pay) − actual price paid

5 important questions

Q1. What is marginal utility?

Marginal utility is the extra satisfaction a consumer gets from consuming one more unit of a good. MUn = TUn − TU(n−1).

Q2. A consumer is ready to pay Rs. 80 for a book but buys it for Rs. 60. Find consumer's surplus.

Consumer's surplus = willingness to pay − price paid = 80 − 60 = Rs. 20.

Q3. Explain the law of diminishing marginal utility with a schedule and diagram.

• Statement of the law.
• Schedule (as in the table above).
• Diagram: MU curve slopes downward from left to right and cuts the X-axis where MU = 0; TU curve rises, reaches a peak, then falls.
• Assumptions and exceptions.
• Importance: basis of law of demand, progressive taxation, value paradox.

Q4. Explain the law of equi-marginal utility.

• Consumer has limited income and many wants.
• He spends so that MU per rupee is equal in all uses.
• Table example with two goods and Rs. 1 units of money.
• Diagram: equal MU lines.
• Uses: consumption, production (factor combination), public finance.
• Limitations: indivisible goods, ignorance, habits.

Q5. Explain Marshall's concept of consumer's surplus and its criticism.

• Meaning: satisfaction above the price paid.
• Measurement: total utility in money minus total amount paid.
• Diagram: area below demand curve and above price line.
• Importance: tax policy, pricing, comparing living standards.
• Criticism: imaginary, hard to measure, assumes constant MU of money, ignores substitutes.

Exam tip

Draw TU and MU curves one above the other with the same X-axis; show TU at its peak exactly where MU touches zero.

Quick summary

Indifference curve analysis is the ordinal approach to consumer behaviour. It was developed by J.R. Hicks and R.G.D. Allen (1934), based on earlier work by Edgeworth and Pareto. The consumer only ranks combinations of goods; utility need not be measured. Equilibrium is found where the budget line touches the highest possible indifference curve.

Key points

• An indifference curve (IC) shows different combinations of two goods that give the consumer the same level of satisfaction. The consumer is indifferent between them.
• An indifference map is a set of ICs; a higher IC shows higher satisfaction.
• They slope downward from left to right (negative slope).
• They are convex to the origin (because of diminishing MRS).
• Two ICs never cut each other.
• A higher IC gives more satisfaction.
• An IC usually does not touch either axis.
• Properties of ICs:
• Marginal rate of substitution (MRSxy): the amount of good Y the consumer is willing to give up for one more unit of good X, keeping satisfaction the same. It diminishes along an IC.
• The budget line (price line) shows all combinations of two goods a consumer can buy with his income at given prices. Its slope = Px/Py.
• Consumer equilibrium conditions: (1) the budget line is tangent to the IC, i.e. MRSxy = Px/Py; (2) the IC is convex to the origin at that point.
• A change in income shifts the budget line parallel; a change in price of one good rotates it.
• Price effect = Income effect + Substitution effect (Hicks' decomposition).
• The IC approach explains the Giffen paradox, which the utility approach could not.

Important terms

• Indifference (उदासीनता) curve – locus of equal-satisfaction combinations.
• Ordinal utility – satisfaction ranked, not measured.
• Income consumption curve (ICC) – joins equilibrium points as income changes.
• Price consumption curve (PCC) – joins equilibrium points as the price of one good changes.
• Substitution effect – change in demand due to change in relative prices, real income held constant.

Formulas

• MRSxy = −ΔY/ΔX (number of Y given up per extra unit of X)
• Budget equation: M = Px·X + Py·Y (M = money income)
• Slope of budget line = Px/Py
• Equilibrium: MRSxy = Px/Py
• Price effect = Income effect + Substitution effect

5 important questions

Q1. What is an indifference curve?

It is a curve showing different combinations of two goods that give equal satisfaction to the consumer. So the consumer has no preference between any two points on it.

Q2. A consumer has Rs. 100. Px = Rs. 10, Py = Rs. 5. Write the budget equation and find the maximum of each good.

• Budget equation: 100 = 10X + 5Y.
• Only X: X = 100/10 = 10 units. Only Y: Y = 100/5 = 20 units.
• Slope of budget line = Px/Py = 10/5 = 2.

Q3. Explain the properties of indifference curves with diagrams.

• Negative slope: more X needs less Y to keep satisfaction same.
• Convex to origin: diminishing MRS.
• Never intersect: would give contradictory satisfaction levels (transitivity).
• Higher IC = higher satisfaction (more of both goods).
• Do not touch axes: consumer wants both goods.

Q4. Explain consumer's equilibrium with indifference curves.

• Assumptions: rational consumer, fixed income and prices, ordinal utility.
• Draw indifference map and budget line.
• Equilibrium at point of tangency: MRSxy = Px/Py.
• Points on higher IC unaffordable; points on lower IC give less satisfaction.
• Second condition: IC convex at the point.

Q5. Compare the cardinal utility and indifference curve approaches.

• Measurement: cardinal (utils) vs ordinal (ranking).
• Assumption of constant MU of money vs none needed.
• Tool: MU curve vs IC and budget line.
• Price effect split into income and substitution effects only in IC.
• IC explains Giffen paradox; it is more realistic.

Exam tip

Name Hicks and Allen in your first line. In the equilibrium diagram, mark the tangency point clearly and write MRSxy = Px/Py below it.

Quick summary

Consumers often get more satisfaction from a good than the price they actually pay. Alfred Marshall called this extra benefit consumer surplus. It is the difference between what a consumer is willing to pay and what he actually pays. The idea is built on the law of diminishing marginal utility and is useful in taxation, pricing and welfare policy.

Key points

• Definition (Marshall): "The excess of the price which a consumer would be willing to pay rather than go without the thing, over that which he actually does pay."
• A consumer buys units until marginal utility (in money) equals price. Earlier units give more utility than the price, so a surplus arises on them.
• Consumer surplus = Potential price (total utility in money) − Actual price paid (P × Q).
• On a diagram it is the area below the demand curve and above the price line.
• Assumptions: utility is measurable in money (cardinal), marginal utility of money is constant, diminishing marginal utility, independent utilities, no substitutes considered.
• Hicks' view: measured it with indifference curves (compensating variation), avoiding cardinal measurement.
• Criticisms: utility cannot be measured exactly; MU of money is not constant; hypothetical (imaginary); hard to measure for necessities whose potential price is infinite; ignores substitutes; differs between rich and poor.
• Importance: a monopolist and price discrimination; finance minister in choosing taxes (tax goods where surplus is large, causing less loss); comparing living standards; benefit from foreign trade and public projects (cost-benefit analysis); explains the paradox of value (water and diamonds).
• Consumer surplus is larger for necessities that are cheap (salt, matchbox).

Important terms

• Potential price – the maximum a consumer would pay rather than go without.
• Actual price – the market price paid.
• Consumer surplus (उपभोक्त्याचे संतोषाधिक्य) – the gain = potential price − actual price.
• Marginal utility of money – the satisfaction from the last rupee, assumed constant.

Formulas

• CS = Σ MU (in ₹) − (P × Q)

The consumer buys 4 units (MU = P). CS = 59 − 40 = ₹19.

5 important questions

Q1. Define consumer surplus.

It is the difference between the price a consumer is willing to pay for a good rather than go without it and the price he actually pays.

Q2. Name two assumptions of Marshall's concept.

Utility can be measured in money, and the marginal utility of money remains constant.

Q3. Explain Marshall's concept of consumer surplus with a schedule and diagram.

Outline: definition; assumptions; schedule (as above); diagram – downward demand (MU) curve, price line, shaded area = CS; how the consumer stops at MU = P.

Q4. State the criticisms of the doctrine of consumer surplus.

Outline: imaginary/hypothetical; cardinal measurement impossible; MU of money changes; necessities give infinite surplus; ignores substitutes and complementaries; differs with income; Hicks' indifference-curve restatement.

Q5. Explain the practical importance of consumer surplus.

Outline: pricing by monopolist and price discrimination; taxation policy; cost-benefit analysis of public projects; gains from international trade; comparing welfare between places; distinction between value-in-use and value-in-exchange.

Exam tip

Always shade the area between the demand curve and the price line and label it "Consumer Surplus" – it is the main mark-earner in the diagram.

Quick summary

Production means creating goods and services that have utility. The theory of production studies the relation between inputs (factors) and output. This topic covers factors of production, the production function, the law of variable proportions (short run) and returns to scale (long run).

Key points

• Factors of production: land, labour, capital and organisation (entrepreneur). Their rewards are rent, wages, interest and profit.
• Production function: Q = f(L, K) – output depends on inputs of labour (L) and capital (K) with a given technology.
• Short run: at least one factor is fixed. Long run: all factors can be changed.
• Law of variable proportions (short run): when more units of a variable factor are added to fixed factors, total product first rises at an increasing rate, then at a decreasing rate, and finally falls.
• Stage I – increasing returns: AP rises throughout; MP rises at first, then starts falling (but stays above AP); TP rises fast. Stage I ends where AP is at its maximum (AP = MP).
• Stage II – diminishing returns: MP falls but is positive; AP falls; TP rises at a decreasing rate and reaches its maximum when MP = 0.
• Stage III – negative returns: MP is negative; TP falls.
• Three stages of the law:
• A rational producer always works in Stage II.
• Causes of diminishing returns: fixed factor becomes scarce relative to variable factor; factors are imperfect substitutes.
• Increasing returns – output rises by a larger proportion.
• Constant returns – output rises by the same proportion.
• Diminishing returns – output rises by a smaller proportion.
• Returns to scale (long run): all inputs increased in the same proportion.
• Increasing returns come from economies of scale; diminishing returns from diseconomies of scale.
• Isoquant (equal product curve): combinations of L and K giving the same output. Isocost line: combinations the firm can buy with a given outlay. Least-cost combination is where the isoquant touches the isocost line.

Important terms

• Total product (TP) – total output from all units of variable factor.
• Average product (AP) – output per unit of variable factor.
• Marginal product (MP) – extra output from one more unit of variable factor.
• Entrepreneur (उद्योजक) – the person who organises production and bears risk.
• Internal economies – cost advantages from a firm's own growth.
• External economies – advantages from growth of the whole industry.

Formulas

• AP = TP / L
• MPn = TPn − TP(n−1) = ΔTP/ΔL
• MRTS(L,K) = ΔK/ΔL (slope of isoquant)
• Least-cost combination: MRTS(L,K) = w/r (w = wage, r = price of capital)

5 important questions

Q1. What is a production function?

It is the technical relation between physical inputs and physical output: Q = f(L, K). It shows the maximum output from given inputs with given technology.

Q2. TP with 4 workers is 40 and with 5 workers is 48. Find MP of the 5th worker and AP at 5 workers.

• MP = 48 − 40 = 8 units.
• AP = 48/5 = 9.6 units.

Q3. Explain the law of variable proportions with a schedule and diagram.

• Statement; assumptions (one fixed factor, homogeneous units, constant technology).
• Schedule as above.
• Diagram: TP rises, flattens, falls; AP and MP inverted-U shaped; MP cuts AP at AP's maximum.
• Three stages and features.
• Producer operates in stage II.

Q4. Explain returns to scale.

• Long-run concept: all factors change in same proportion.
• Increasing, constant, diminishing returns with example (doubling inputs).
• Causes: division of labour, specialisation, indivisibility; later management problems.
• Difference from law of variable proportions.

Q5. Explain internal and external economies of scale.

• Internal: technical, managerial, marketing, financial, risk-bearing.
• External: localisation of industry, better transport, skilled labour pool, ancillary industries, information.
• Diseconomies: management difficulty, high factor prices, congestion.

Exam tip

Remember: MP cuts AP at its highest point, and TP is maximum when MP is zero. Examiners often ask this relation.

Quick summary

Cost is the money a firm spends on inputs to produce output. Revenue is the money a firm receives from selling its output. This topic explains the types of cost, short-run cost curves, the long-run average cost curve, and total, average and marginal revenue.

Key points

• Money cost is the total money spent on production. Real cost is the pain and sacrifice of factor owners (Marshall). Opportunity cost is the next best alternative given up.
• Explicit cost: actual payments to outsiders (wages, rent, raw material). Implicit cost: value of the owner's own factors (own building, own capital, own salary).
• Fixed cost (FC) does not change with output (rent, salary of permanent staff, insurance). It exists even at zero output. Variable cost (VC) changes with output (raw material, power, daily wages).
• TC = TFC + TVC. TFC curve is a horizontal line; TVC starts from the origin; TC starts from the level of TFC and runs parallel to TVC.
• AFC falls continuously as output rises (a rectangular hyperbola). AVC, AC and MC are U-shaped because of the law of variable proportions.
• MC cuts AVC and AC at their minimum points from below.
• Long-run average cost (LAC) curve is the envelope of short-run AC curves. It is also U-shaped (flatter), because of economies and then diseconomies of scale. It is also called the planning curve.
• Revenue: TR = price × quantity. AR = TR/Q = price. MR = change in TR from one more unit sold.
• Under perfect competition, price is constant, so AR = MR and the AR curve is a horizontal straight line.
• Under monopoly and monopolistic competition, the firm must lower price to sell more, so AR slopes downward and MR lies below AR.
• When MR is zero, TR is maximum; when MR is negative, TR falls.

Important terms

• Cost (खर्च) of production – total expenditure on inputs.
• Marginal cost (MC) – addition to TC from one more unit of output.
• Normal profit – minimum profit to keep a firm in the industry; part of cost.
• Break-even point – where TR = TC (no profit, no loss).
• Shutdown point – where price = minimum AVC; below it the firm stops production in the short run.

Formulas

• TC = TFC + TVC
• AFC = TFC/Q; AVC = TVC/Q; AC = TC/Q = AFC + AVC
• MCn = TCn − TC(n−1) = ΔTC/ΔQ
• TR = P × Q; AR = TR/Q = P; MR = ΔTR/ΔQ
• Relation: MR = AR × (e − 1)/e, where e = price elasticity of demand

5 important questions

Q1. Distinguish between fixed cost and variable cost.

Fixed cost does not change with output and exists even at zero output, e.g. rent. Variable cost changes directly with output and is zero at zero output, e.g. raw material.

Q2. TC of 10 units is Rs. 500 and of 11 units is Rs. 540. TFC is Rs. 100. Find MC of the 11th unit and AVC at 11 units.

• MC = 540 − 500 = Rs. 40.
• TVC at 11 units = 540 − 100 = 440; AVC = 440/11 = Rs. 40.

Q3. Explain the short-run cost curves with a diagram.

• TFC horizontal; TVC from origin; TC parallel to TVC above it.
• AFC falls continuously.
• AVC, AC, MC U-shaped due to variable proportions.
• MC cuts AVC and AC at their lowest points.
• Gap between AC and AVC = AFC, which narrows as output rises.

Q4. Why is the long-run average cost curve U-shaped and flatter?

• In the long run all factors are variable.
• LAC is the envelope of SAC curves (Viner's envelope curve).
• First falls due to economies of scale; then rises due to diseconomies.
• Flatter because the firm can adjust plant size.

Q5. Explain the relation between AR and MR under different market forms.

• Perfect competition: price constant; AR = MR; horizontal line.
• Monopoly/monopolistic competition: AR slopes downward; MR below AR and falls faster.
• For a straight-line AR, MR cuts the X-axis halfway.
• TR maximum where MR = 0.

Exam tip

Draw AC, AVC and MC on one diagram and make the MC curve pass through the lowest points of both — this single detail carries marks.

Quick summary

Perfect competition is a market with a very large number of buyers and sellers selling an identical product at a single market price. No individual firm can affect price; the firm is a price taker. This topic covers its features, price determination by demand and supply, and the equilibrium of the firm in the short run and long run.

Key points

• Large number of buyers and sellers.
• Homogeneous (identical) product.
• Free entry and exit of firms.
• Perfect knowledge of the market.
• Perfect mobility of factors.
• No transport cost (one uniform price).
• No government interference.
• Features:
• Price is fixed by the industry through the interaction of market demand and market supply. The firm accepts that price.
• The firm's demand (AR) curve is a horizontal straight line; AR = MR = Price.
• Conditions of firm's equilibrium: (1) MC = MR; (2) MC curve cuts MR from below (MC rising).
• Short run: a firm may earn supernormal profit (AR > AC), normal profit (AR = AC) or bear loss (AR < AC). It continues production as long as price covers AVC.
• Long run: due to free entry and exit, supernormal profits and losses disappear. Every firm earns only normal profit.
• Long-run equilibrium condition: Price = AR = MR = MC = minimum LAC. Firms work at the optimum size.
• Marshall's time element: market period (supply fixed, price depends on demand), short period, long period and secular period.
• Pure competition has only the first three features; perfect competition has all.
• Perfect competition is rare in real life; agricultural markets come closest.

Important terms

• Price taker – a firm that cannot change the market price.
• Industry – the group of all firms producing the same good.
• Supernormal (abnormal) profit – profit above normal profit, when AR > AC.
• Optimum firm – a firm producing at minimum average cost.
• Equilibrium (समतोल) price – price at which market demand equals market supply.

Formulas

• Equilibrium price: Qd = Qs
• Firm's equilibrium: MC = MR and MC rising
• Under perfect competition: P = AR = MR
• Total profit = (AR − AC) × Q
• Long run: P = MC = minimum LAC

5 important questions

Q1. Why is a firm a price taker under perfect competition?

Each firm supplies a very small part of total supply and the product is identical. If it charges more, buyers go to other sellers. So it must accept the price set by the industry.

Q2. Demand: Qd = 100 − 2P; supply: Qs = 20 + 2P. Find equilibrium price and quantity.

• At equilibrium Qd = Qs: 100 − 2P = 20 + 2P.
• 80 = 4P, so P = Rs. 20.
• Q = 100 − 2(20) = 60 units.

Q3. Explain the features of perfect competition.

• List and explain the seven features above.
• Effect of each feature on price (one uniform price).
• Difference between pure and perfect competition.

Q4. Explain the short-run equilibrium of a firm under perfect competition.

• Conditions MC = MR, MC rising.
• Case 1: AR > AC – supernormal profit.
• Case 2: AR = AC – normal profit.
• Case 3: AR < AC but > AVC – loss, firm continues.
• Shutdown point at minimum AVC.
• Diagram for each case.

Q5. Explain the long-run equilibrium of firm and industry.

• Free entry removes supernormal profit; free exit removes losses.
• Firm earns normal profit at the minimum point of LAC.
• Condition: P = AR = MR = LMC = LAC.
• Industry in equilibrium when no firm wants to enter or leave.

Exam tip

Learn the two equilibrium conditions (MC = MR and MC cutting from below). Draw the industry diagram beside the firm diagram to show how price is fixed.

Quick summary

Monopoly is a market with a single seller of a product that has no close substitute. Monopolistic competition, a concept given by E.H. Chamberlin (1933), has many sellers selling similar but differentiated products. Joan Robinson's work on imperfect competition (1933) is also important. This topic covers features, equilibrium, price discrimination and selling costs.

Key points

• Features of monopoly: single seller, no close substitutes, strong barriers to entry, firm = industry, price maker.
• Sources of monopoly: patents and licences, control of raw material, huge capital needs, government ownership (railways), natural monopoly.
• Monopolist's AR curve slopes downward; MR lies below AR.
• Equilibrium: MC = MR and MC cuts MR from below. Price is read from the AR curve above that output.
• A monopolist may earn supernormal profit even in the long run because entry is blocked.
• A monopolist always produces where demand is elastic (e > 1), because MR is positive only there.
• Price discrimination: charging different prices to different buyers for the same product. Possible when markets can be separated and elasticities differ. More is charged in the market with less elastic demand.
• Pigou's three degrees of price discrimination: first degree (each buyer pays his maximum price), second degree (prices by blocks of quantity), third degree (buyers divided into groups or markets).
• Features of monopolistic competition: many sellers, product differentiation (brand, packing, design), free entry and exit, selling costs, some control over price.
• The firm's demand curve slopes downward but is more elastic than a monopolist's because close substitutes exist.
• Short run: profit or loss possible. Long run: free entry removes supernormal profit; AR is tangent to LAC; normal profit only.
• Long-run equilibrium is to the left of minimum LAC, so there is excess capacity.
• Examples: soaps, toothpaste, restaurants, clothing brands.

Important terms

• Price maker – a firm that decides its own price.
• Product differentiation – making a product appear different from rivals' products.
• Selling costs – spending on advertisement and sales promotion (Chamberlin).
• Excess capacity – gap between actual output and optimum (minimum-cost) output.
• Monopoly (मक्तेदारी) – market with one seller.
• Dumping – selling at a lower price abroad than at home; a form of discrimination.

Formulas

• Equilibrium: MC = MR, MC rising
• MR = AR × (e − 1)/e
• Profit = (AR − AC) × Q
• Under discrimination: MR₁ = MR₂ = MC (MR equal in both markets and equal to total MC)
• Lerner's degree of monopoly power = (P − MC)/P

5 important questions

Q1. What is price discrimination?

It means charging different prices for the same product from different buyers, for reasons not related to cost. Example: lower fees for students, different electricity rates for homes and industries.

Q2. AR = Rs. 30 and elasticity of demand = 3. Find MR.

• MR = AR × (e − 1)/e = 30 × (3 − 1)/3 = 30 × 2/3 = Rs. 20.

Q3. Explain price and output determination under monopoly.

• Features of monopoly.
• AR and MR curves sloping down, MR below AR.
• Equilibrium where MC = MR and MC rising.
• Price from AR; profit = (AR − AC) × Q.
• Short-run loss possible; long-run supernormal profit possible.
• Diagram.

Q4. Explain the features of monopolistic competition.

• Many sellers, product differentiation, selling costs, free entry, non-price competition.
• Demand curve elastic, downward sloping.
• Mixture of monopoly and competition.
• Examples.

Q5. Explain long-run equilibrium under monopolistic competition and excess capacity.

• New firms enter due to profit; each firm's demand falls.
• AR becomes tangent to LAC: only normal profit.
• Tangency to the left of LAC minimum.
• Output less than optimum: excess capacity, higher price than under perfect competition.
• Diagram.

Exam tip

Always state Chamberlin with "product differentiation" and "selling costs" — these two words are what examiners look for in monopolistic competition answers.

Quick summary

Oligopoly is a market with a few large sellers, each big enough to affect the market price. Because the sellers are few, every firm watches and reacts to its rivals: this interdependence is the key feature. Indian examples include telecom (Jio, Airtel, Vi), cement, cars and aviation. The kinked demand curve and price leadership explain why prices in oligopoly tend to stay rigid.

Key points

• Few sellers, many buyers; products may be homogeneous (pure oligopoly – steel, cement) or differentiated (differentiated oligopoly – cars, soft drinks).
• Duopoly is the special case of only two sellers (e.g. Coca-Cola and Pepsi in cola drinks).
• Features: interdependence in decisions, barriers to entry (large capital, patents, economies of scale), heavy advertising and selling costs, price rigidity, indeterminate demand curve, group behaviour, non-price competition.
• Kinked demand curve (Paul Sweezy, 1939): if a firm raises its price, rivals do not follow, so it loses many customers (elastic upper part). If it cuts the price, rivals follow, so it gains few customers (inelastic lower part). The demand curve has a kink at the current price.
• Because of the kink, the MR curve has a gap (discontinuity); MC can move up or down within this gap without changing price or output – this explains price rigidity.
• Collusive oligopoly: firms co-operate. Cartel – formal agreement to fix price/output (e.g. OPEC); price leadership – a dominant or low-cost firm sets the price and others follow.
• Non-collusive oligopoly: firms act independently, e.g. Cournot and kinked-demand models.
• In India, collusion is illegal under the Competition Act, 2002, enforced by the Competition Commission of India (CCI).

Important terms

• Oligopoly (अल्पाधिकार) – market with a few sellers.
• Interdependence – each firm's decision depends on rivals' expected reactions.
• Cartel – a formal group of firms that jointly fix price and output.
• Price rigidity – prices remain unchanged for long periods.
• Selling costs – spending on advertising and sales promotion.

Formulas

• Kinked demand: upper segment elastic (e > 1), lower segment inelastic (e < 1).
• MR = AR × (e − 1)/e; the jump in e at the kink creates the vertical gap in MR.
• Equilibrium: MC passes through the MR gap → price and output stay at the kink.

5 important questions

Q1. What is oligopoly?

A market form in which a few sellers produce identical or differentiated products and each seller's decisions affect the others.

Q2. What is a cartel?

A formal agreement among oligopoly firms to act like a single monopolist by fixing a common price or sharing output. Example: OPEC.

Q3. Explain the main features of oligopoly.

Outline: few sellers; interdependence; entry barriers; advertising and selling costs; price rigidity; indeterminate demand curve; group behaviour; types (pure/differentiated, collusive/non-collusive); Indian examples.

Q4. Explain the kinked demand curve model of oligopoly with a diagram.

Outline: Sweezy's assumptions; behaviour of rivals on price rise and cut; diagram with kink at point K; discontinuous MR; MC shifts within the gap; conclusion – price rigidity; criticisms (does not explain how the initial price is fixed).

Q5. Distinguish between collusive and non-collusive oligopoly. Explain price leadership.

Outline: meaning of each; cartel and price leadership as collusion; types of leadership – low-cost firm, dominant firm, barometric; limits of collusion (cheating, law); Competition Act 2002.

Exam tip

The kinked demand curve diagram must show the gap in the MR curve clearly with MC passing through it.

Quick summary

The theory of distribution (factor pricing) explains how the national income is shared among the four factors of production as rent, wages, interest and profit. The marginal productivity theory, developed by J. B. Clark and others, says that under perfect competition each factor is paid a reward equal to the value of its marginal product. It is the general theory of factor pricing.

Key points

• Personal distribution asks how income is divided among persons; functional distribution asks how it is divided among factors. This topic is about functional distribution.
• Factor rewards: land → rent, labour → wages, capital → interest, entrepreneur → profit.
• Factor prices are decided by the demand for and supply of factors. Demand for a factor is a derived demand – it comes from the demand for the goods it helps produce.
• Statement: under perfect competition, a firm employs a factor up to the point where its price equals its marginal revenue product (MRP); in perfect competition MRP = VMP.
• Marginal physical product (MPP): extra output from one more unit of the factor. VMP = MPP × Price of output. MRP = MPP × MR.
• Because of diminishing returns, MRP falls as more units are employed, so the firm stops where wage = MRP.
• Assumptions: perfect competition in factor and product markets, homogeneous units of a factor, perfect mobility, full employment, diminishing returns, factors are substitutable, long run.
• Criticisms: perfect competition is unreal; units of a factor are not identical; marginal product of a single factor is hard to separate (joint production); ignores supply side; trade unions and bargaining; does not explain fairness; full employment is rare (Keynes).
• Modern theory: factor price is fixed where the demand curve (MRP) and the supply curve of the factor intersect.

Important terms

• Derived demand (व्युत्पन्न मागणी) – demand for a factor arising from demand for the final product.
• MPP – change in total physical output from one more unit of a factor.
• VMP – MPP valued at the product price.
• MRP – addition to total revenue from one more unit of a factor.
• Functional distribution – sharing of national income among factors of production.

Formulas

• VMP = MPP × P; MRP = MPP × MR (equal under perfect competition, since P = MR).
• Firm's equilibrium in the factor market: Factor price (w) = MRP, with MRP falling.

If the wage is ₹60, the firm hires 3 workers (wage = VMP).

5 important questions

Q1. What is derived demand?

The demand for a factor of production is called derived demand because it depends on the demand for the goods and services that factor helps to produce.

Q2. Define marginal revenue product.

MRP is the addition made to a firm's total revenue by employing one more unit of a factor, other factors remaining constant (MRP = MPP × MR).

Q3. Explain the marginal productivity theory of distribution with a schedule and diagram.

Outline: statement (Clark); MPP, VMP, MRP; schedule; diagram of falling MRP/VMP curve and horizontal wage line; firm's equilibrium where w = MRP; industry level.

Q4. State the assumptions and criticisms of the marginal productivity theory.

Outline: list the assumptions; criticisms – unrealistic perfect competition, heterogeneity, joint productivity, immobility, ignores supply and bargaining, ethical issue, full employment; it is a theory of demand for factors only.

Q5. Distinguish between personal and functional distribution. How is factor price determined under the modern theory?

Outline: meanings with examples; modern theory – demand (MRP) and supply of factor; equilibrium diagram; shifts in demand/supply.

Exam tip

Use the words MPP, VMP and MRP correctly – examiners check whether you know that VMP = MRP only under perfect competition.

Quick summary

In economics, rent is the payment for the use of land (and other factors) whose supply is fixed. David Ricardo explained rent as a surplus arising from differences in the fertility and location of land. The modern theory treats rent as a surplus over transfer earnings, which any factor can earn. Marshall's quasi-rent applies the same idea to man-made capital in the short run.

Key points

• Contract rent is the total amount actually paid by a tenant (includes interest on improvements); economic rent is the pure payment for the original powers of the soil.
• Ricardian theory (1817): "Rent is that portion of the produce of the earth which is paid to the landlord for the use of the original and indestructible powers of the soil."
• Rent arises because land is limited and differs in fertility. The least fertile land in use is the marginal (no-rent) land; better lands earn a surplus over it = differential rent.
• Extensive cultivation: as population grows, inferior lands are cultivated; rent on superior lands rises.
• Intensive cultivation: more labour and capital on the same land; the law of diminishing returns creates surplus on earlier doses.
• Ricardo also recognised situation (location) rent – land near the market earns more.
• Criticisms: soil powers are not "indestructible"; order of cultivation may not follow fertility; no-rent land may not exist; ignores scarcity rent; assumes perfect competition and only agricultural use.
• Modern theory (Mrs Joan Robinson, Boulding): Economic rent = Actual earnings − Transfer earnings. Any factor with less than perfectly elastic supply can earn rent; if supply is perfectly inelastic, all earnings are rent.
• Quasi-rent (Marshall): short-run surplus earned by machines and other man-made capital whose supply cannot change quickly; Quasi-rent = TR − TVC. It disappears in the long run.
• Scarcity rent – arises when all land is equally fertile but scarce.

Important terms

• Economic rent (आर्थिक खंड) – surplus over the minimum earning needed to keep a factor in its present use.
• Transfer earnings – the minimum a factor can earn in its next best alternative use.
• Marginal land – land that just covers its cost of cultivation and earns no rent.
• Differential rent – surplus of superior land over marginal land.
• Quasi-rent – temporary surplus of man-made factors in the short run.

Formulas

• Ricardian rent of a plot = Its output − Output of marginal land (same inputs)
• Modern: Economic rent = Actual earnings − Transfer earnings
• Quasi-rent = TR − TVC

Example (modern): a teacher earns ₹60,000 per month; next best job pays ₹45,000 → economic rent = ₹15,000.

5 important questions

Q1. What is economic rent according to the modern theory?

It is the excess of a factor's actual earnings over its transfer earnings (what it could earn in its next best use).

Q2. What is quasi-rent?

Marshall's term for the surplus (TR − TVC) earned in the short run by machines and other man-made capital whose supply is temporarily fixed.

Q3. Explain Ricardo's theory of rent with extensive and intensive cultivation.

Outline: definition; assumptions; differential rent with a table of land grades; extensive margin; intensive margin with doses of capital; situation rent; diagram.

Q4. Critically examine the Ricardian theory of rent.

Outline: criticisms – indestructible powers, historical order of cultivation, no-rent land, scarcity rent ignored, perfect competition, rent and price relation; partial validity; contribution to the modern theory.

Q5. Explain the modern theory of rent. Distinguish between rent and quasi-rent.

Outline: Joan Robinson's transfer earnings; rent with different supply elasticities (perfectly inelastic, elastic, perfectly elastic – diagrams); quasi-rent meaning; table of differences (factor, period, nature, permanence).

Exam tip

Always distinguish contract rent and economic rent in the introduction – it is a common 2-mark question.

Quick summary

Wages are the reward paid for the services of labour, physical or mental. Economists have offered several theories to explain how the wage rate is fixed: the subsistence theory, the wage fund theory, the residual claimant theory, the marginal productivity theory and the modern demand-and-supply theory. Trade unions and collective bargaining also influence wages in real life.

Key points

• Nominal (money) wages: wages paid in money. Real wages: the goods and services money wages can buy; they depend on prices, extra benefits, regularity of work, working conditions and future prospects.
• Time wages are paid per hour/day/month; piece wages per unit of output.
• Subsistence theory (Physiocrats, Ricardo; "iron law of wages" – Lassalle): wages tend to settle at the minimum needed for workers' survival because higher wages raise population and labour supply. Criticised for ignoring productivity and for being pessimistic.
• Wage fund theory (J. S. Mill): average wage = wage fund ÷ number of workers; the fund is fixed in the short run. Mill himself withdrew it in 1869.
• Residual claimant theory (F. A. Walker): workers get what is left after paying rent, interest and profit.
• Marginal productivity theory: under perfect competition, wage = MRP (= VMP) of labour; firms hire labour until the two are equal.
• Modern theory: the wage rate is fixed where the demand for labour (derived from MRP) equals the supply of labour (depends on population, work-leisure choice, mobility, training).
• The individual labour supply curve may be backward-bending – after a high wage, workers prefer more leisure.
• Trade unions can raise wages through collective bargaining, by restricting labour supply, or by raising productivity; minimum wage laws (Code on Wages, 2019 in India) also affect wages.
• Wage differences arise from skill, training, risk, nature of work, location, and discrimination.

Important terms

• Real wages (वास्तव वेतन) – purchasing power of money wages.
• Collective bargaining – negotiation of wages and conditions between unions and employers.
• Minimum wage – the lowest wage fixed by law.
• Backward-bending supply curve – labour supply falls after a certain high wage.
• Wage differentials – differences in wages between jobs or regions.

Formulas

• Real wage = Money wage ÷ Price index × 100
• Wage fund theory: Average wage = Wage fund ÷ Number of workers
• Equilibrium: Demand for labour (MRP) = Supply of labour

Example: money wage rises from ₹10,000 to ₹12,000 while the price index rises from 100 to 125. Real wage = 12,000 ÷ 125 × 100 = ₹9,600 – the worker is worse off than before.

5 important questions

Q1. Distinguish between money wages and real wages.

Money wages are the amount of money paid to a worker; real wages are the goods and services that money can buy, including extra benefits and work conditions.

Q2. What is the iron law of wages?

The subsistence idea, named by Lassalle, that wages always tend to fall to the bare minimum needed for workers to survive.

Q3. Critically explain the subsistence and wage fund theories of wages.

Outline: statements, authors, logic (Malthusian population; fixed fund); criticisms – ignores productivity and demand side, fund not fixed, no explanation of differences; Mill's withdrawal.

Q4. Explain the modern theory of wage determination with a diagram.

Outline: demand for labour (MRP, derived demand, factors); supply of labour (population, work-leisure choice, backward-bending curve); equilibrium diagram; changes in demand/supply.

Q5. What is the role of trade unions in raising wages?

Outline: collective bargaining; restricting supply; raising productivity; strikes; limits (unemployment risk, employer's capacity, unorganised sector in India); minimum wage laws.

Exam tip

Use one numerical example of real wages – it proves you understand that a money wage rise can still be a real wage fall.

Quick summary

Interest is the price paid for the use of capital (loanable funds), and profit is the reward of the entrepreneur for organising production and bearing risk. Classical, neo-classical (loanable funds) and Keynesian (liquidity preference) theories explain interest. Profit is explained by the risk-bearing (Hawley), uncertainty-bearing (Knight) and innovation (Schumpeter) theories, among others.

Key points

• Gross interest = net (pure) interest + payment for risk + payment for management + reward for inconvenience. Net interest is the pure payment for the use of capital.
• Classical theory: interest is fixed by the demand for capital (investment, depends on its productivity) and the supply of capital (savings, a reward for waiting/abstinence); equilibrium where saving = investment.
• Loanable funds theory (Wicksell, Robertson, Ohlin): interest is fixed by the demand for and supply of loanable funds. Supply = savings + bank credit + dishoarding + disinvestment. Demand = investment + hoarding + consumption loans.
• Liquidity preference theory (Keynes, 1936): interest is the reward for parting with liquidity. It is fixed by the demand for money (liquidity preference) and the supply of money (fixed by the central bank).
• Keynes' three motives for holding money: transactions, precautionary, speculative. The speculative demand is inversely related to the interest rate.
• Liquidity trap: at a very low interest rate, demand for money becomes perfectly elastic; more money cannot lower the rate further.
• Gross profit = net profit + rent, wages and interest on the owner's own factors + depreciation. Net (pure) profit is the reward for entrepreneurship.
• Risk theory (F. B. Hawley): profit is the reward for bearing risk.
• Uncertainty theory (F. H. Knight): insurable risks are costs; profit is the reward for bearing non-insurable uncertainty (changes in demand, competition, policy).
• Innovation theory (J. A. Schumpeter): profit arises from innovations – new product, new method, new market, new source of raw material, new organisation; it disappears when others imitate.
• Normal profit is the minimum needed to keep the entrepreneur in the industry; super-normal profit is above it.

Important terms

• Liquidity preference (तरलता पसंती) – desire to hold wealth as cash.
• Loanable funds – funds available for lending in the market.
• Liquidity trap – a floor rate of interest where demand for money is infinitely elastic.
• Non-insurable risk – uncertainty that cannot be calculated or insured.
• Innovation – putting a new idea into commercial use.

Formulas

• Classical equilibrium: S(i) = I(i)
• Loanable funds: S + ΔM + DH = I + H (equilibrium rate i)
• Keynes: L = L1(Y) + L2(i); equilibrium where L = M (money supply)

5 important questions

Q1. Distinguish between gross interest and net interest.

Net interest is the pure payment for the use of capital. Gross interest includes net interest plus payments for risk, management and inconvenience.

Q2. What is Knight's view of profit?

Profit is the reward for bearing non-insurable risks or uncertainty, which cannot be calculated in advance.

Q3. Explain Keynes' liquidity preference theory of interest.

Outline: meaning of interest; three motives; L1 and L2 curves; money supply vertical line; equilibrium diagram; effect of increase in money supply; liquidity trap; criticisms (ignores real factors, indeterminate – Hansen).

Q4. Explain the loanable funds theory of interest and compare it with the classical theory.

Outline: sources of supply and demand of loanable funds; equilibrium diagram; merits (includes bank credit and hoarding); comparison table with classical.

Q5. Discuss the risk, uncertainty and innovation theories of profit.

Outline: Hawley – risk; Knight – insurable vs non-insurable; Schumpeter – five types of innovation, profit temporary; criticisms of each; conclusion.

Exam tip

For Keynes' theory, list the three motives with one example each – it is the most-asked part.