Foundational terms and ideas tested in CDS, NDA & AFCAT — clearly explained.
Economics in CDS/NDA/AFCAT is tested at a general awareness level — not degree-level theory. You need to know key definitions, the difference between types of economies, how basic markets work, and standard terms like GDP, inflation, and opportunity cost. This chapter covers everything you need from scratch.
Economics is the study of how individuals, businesses and governments make choices about using limited resources to satisfy unlimited wants. The core problem economics tries to solve is called the problem of scarcity.
Lionel Robbins (1932): "Economics is the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses."
Economics is divided into two main branches:
| Branch | What it studies | Example question |
|---|---|---|
| Microeconomics | Individual units — a person, a firm, a market | How does the price of onions change when supply falls? |
| Macroeconomics | The economy as a whole — national income, inflation, employment | Why does India's GDP grow faster in some years? |
CDS/NDA questions often ask you to classify a statement as micro or macro. Individual price, individual firm, individual consumer = Micro. GDP, unemployment rate, inflation = Macro.
Scarcity means that resources (land, labour, capital, time) are limited, but human wants are unlimited. Because of scarcity, every choice involves giving up something else.
Opportunity cost is the value of the next best alternative you give up when making a choice. It is not just about money — it includes time and other benefits foregone.
A soldier gets one hour of free time. He can either sleep or call home. If he chooses to sleep, the opportunity cost is the phone call he missed. Opportunity cost is always the single best alternative foregone — not all alternatives.
Opportunity cost is NOT the money you spend. It is what you give up. If you spend ₹500 on a book you could have spent on food, the opportunity cost is the food — not the ₹500.
Every country must answer three basic questions: What to produce? How to produce? For whom to produce? The way a country answers these determines its economic system.
| Type | Who decides? | Examples |
|---|---|---|
| Market / Capitalist | Private individuals and firms; prices set by demand and supply | USA, UK |
| Planned / Socialist | Government controls production, prices, and distribution | Former USSR, Cuba, North Korea |
| Mixed Economy | Both private sector and government play a role | India, France, Brazil |
India adopted a mixed economy model after independence in 1947. The Nehruvian model emphasised a strong public sector alongside a private sector. This is a frequently asked fact in CDS/NDA.
The Law of Demand states: All else being equal, when the price of a good rises, the quantity demanded falls — and vice versa. This inverse relationship between price and demand is one of the most basic laws in economics.
When the price of petrol rises, people reduce car usage and use public transport more. Quantity demanded for petrol falls as its price rises.
Giffen goods = very cheap inferior goods, poor consumers. Veblen goods = luxury/prestige goods, rich consumers. Both are exceptions to the law of demand, but the reasons are completely different.
The Law of Supply states: All else being equal, when the price of a good rises, producers are willing to supply more of it. This is a direct (positive) relationship — opposite to demand.
If wheat prices rise, farmers are motivated to grow more wheat. Supply of wheat increases with higher prices.
Market Equilibrium is the point where quantity demanded = quantity supplied. The price at this point is called the equilibrium price or market-clearing price.
All production requires inputs called Factors of Production. Classically there are four:
| Factor | What it includes | Reward paid |
|---|---|---|
| Land | All natural resources — soil, water, minerals, forests | Rent |
| Labour | Human effort — physical and mental work | Wages / Salary |
| Capital | Man-made aids to production — machines, tools, buildings, money | Interest |
| Enterprise / Entrepreneur | Person who organises the other three factors and takes risk | Profit |
Physical capital = machines, tools, buildings (man-made). Human capital = skills, education, health of workers. Both are asked in CDS. Note that money itself is not capital in economics — it is only capital when invested in productive assets.
| Type | Meaning | Example |
|---|---|---|
| Free Goods | Available in unlimited quantity; no price | Sunlight, air |
| Economic Goods | Scarce, have a price | Food, clothes, fuel |
| Public Goods | Non-excludable + non-rival; government provides | Street lights, national defence |
| Private Goods | Excludable + rival; bought by individuals | Food, car, mobile phone |
| Normal Goods | Demand rises when income rises | Branded clothes, restaurants |
| Inferior Goods | Demand falls when income rises | Cheap local bread, bus travel |
A government-provided good is NOT necessarily a public good. Railway services are provided by the government but are excludable (you need a ticket) and rival (a seat taken is not available to others). So railway service is a private good provided by the government.
Utility is the satisfaction or benefit a consumer gets from consuming a good or service. The Law of Diminishing Marginal Utility states that as you consume more units of a good, each additional unit gives less satisfaction.
The first glass of water on a hot day is very satisfying. The second is less so. By the fifth glass, you may not want any more. Each additional glass gives less utility.
Elasticity of Demand measures how much the quantity demanded changes when price changes.
| Type | Meaning | Example |
|---|---|---|
| Elastic demand | Big change in demand for small price change | Luxury goods, branded items |
| Inelastic demand | Small change in demand even for large price change | Medicines, salt, petrol |
| Perfectly inelastic | Demand does not change at all with price | Life-saving drugs |
Consumer Surplus is the difference between what a consumer is willing to pay and what they actually pay. If you are willing to pay ₹100 for a book but buy it for ₹70, your consumer surplus is ₹30.
Necessities (salt, medicines) have inelastic demand. Luxuries have elastic demand. This is because consumers have no substitute for necessities but can easily switch away from luxuries when prices rise.