📘 Basic Concepts of Economics

📌 1. Economics: Meaning & Branches

Economics studies how limited resources (scarcity) are used to meet unlimited wants. The central problems are what, how and for whom to produce.

• Adam Smith — "Father of Economics", book The Wealth of Nations (1776).
• J. M. Keynes — father of macroeconomics, General Theory (1936).
• Opportunity cost = value of the next best alternative given up.

📌 2. Economic Systems

• India adopted a mixed economy after independence (Industrial Policy 1948, 1956).
• India is a developing economy; the market's role grew after the 1991 liberalisation.

📌 3. Sectors of the Economy

• The services sector has the largest share of India's GDP (GVA), while agriculture still employs the most people.
• Quaternary = knowledge-based (research, IT, education); quinary = top decision-makers.
• The organised sector is registered and follows rules; most workers are in the unorganised sector with little job security.

📌 4. Demand, Supply & Elasticity

• Law of demand: other things equal, a rise in price lowers quantity demanded (inverse relation); the demand curve slopes downward.
• Law of supply: a higher price raises quantity supplied (direct relation).
• Equilibrium price is set where demand = supply.
• Giffen goods (a special inferior good) and Veblen/prestige goods are exceptions to the law of demand.
• Price elasticity of demand = % change in demand ÷ % change in price. Necessities like salt and medicines are inelastic; luxuries are elastic.

📌 5. Market Forms

📌 6. Production Possibility Curve (PPC)

Every economy faces the central problems of what to produce, how to produce and for whom — because resources are scarce and have alternative uses. The PPC (production possibility frontier / transformation curve) shows the maximum combinations of two goods that can be produced when given resources and technology are fully and efficiently used.

• The PPC is concave to the origin because the marginal opportunity cost (MRT) keeps rising; with constant opportunity cost it is a straight line.
• Slope = MRT = ΔY/ΔX = units of Y given up for one more unit of X.
• A point on the curve = full and efficient use; inside = unemployment / under-use; outside = unattainable with present resources.
• The PPC shifts right with more resources or better technology (economic growth) and left when resources are destroyed (war, earthquake). If technology improves for only one good, the curve rotates along that axis.

📌 7. Consumer Behaviour: Utility and Indifference Curve

• An indifference curve (IC) = combinations of two goods giving equal satisfaction. It was introduced by Edgeworth, developed by Pareto and popularised by Hicks and Allen.
• Properties: slopes downward; convex to the origin (diminishing MRS); two ICs never intersect; a higher IC = more satisfaction.
• MRSxy = ΔY/ΔX = MUx/MUy. Budget line: Px·X + Py·Y = M, slope = −Px/Py.
• Perfect substitutes: straight-line IC; perfect complements (e.g. left and right shoes): L-shaped IC.
• Price effect = substitution effect + income effect.

📌 8. Production and Cost: Law of Variable Proportions, Returns to Scale

Production function Q = f(L, K). Factors and their rewards: land — rent, labour — wages, capital — interest, entrepreneur — profit. In the short run at least one factor is fixed; in the long run all factors are variable.

• Returns to scale (long run, all inputs raised in the same proportion): output rises more than proportionately = increasing (IRS); equally = constant (CRS); less = decreasing (DRS).
• Cobb–Douglas Q = A·L^α·K^β: α + β > 1 → IRS; = 1 → CRS; < 1 → DRS.
• Costs: TC = TFC + TVC; AC = AFC + AVC; MC = ΔTC/ΔQ. AFC falls continuously (a rectangular hyperbola). AC, AVC and MC are U-shaped; MC cuts AC and AVC at their minimum points.
• Long-run AC = envelope curve; its U-shape comes from economies and diseconomies of scale.

📌 9. Practice MCQs