Q.Demand curve in perfect competition is -
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Perfect Competition
Perfect competition is one of those ideas in economics that sounds technical but actually describes something you see every day — a market where no single seller has any real power, and the price is just… the price.
The everyday intuition
Think of a vegetable market in your town. There are dozens of vendors selling tomatoes. All the tomatoes are more or less the same. You can walk from one stall to another and buy from anyone. If one vendor tries to charge ₹10 more per kilo than the others, you simply walk to the next stall. That vendor loses customers instantly. So every vendor ends up charging the same price — the market price. No one decides it; it just emerges from everyone buying and selling.
That’s the core feel of perfect competition: price-takers, not price-makers.
The precise meaning
In economics, a market is called perfectly competitive when it satisfies five conditions. NCERT Class-12 (Introductory Microeconomics, Chapter 4) lists them clearly:
- Large number of buyers and sellers — so many that no single buyer or seller can influence the market price by their own action.
- Homogeneous product — the good sold by every firm is identical. No branding, no quality difference. A buyer has no reason to prefer one seller over another.
- Perfect information — every buyer and seller knows the price prevailing in the market. No one is tricked into paying more.
- Free entry and exit — any new firm can start producing and selling, and any existing firm can shut down and leave, without legal or cost barriers.
- No transaction costs — buyers and sellers can trade directly without extra expenses like transport or middlemen.
When all five hold, the market is perfectly competitive. In reality, no market is perfectly competitive — but agricultural markets, stock markets for widely traded shares, and online commodity markets come close.
Why it matters
Perfect competition is the benchmark — the ideal against which all real markets are compared. It tells us what happens when competition is at its maximum.
The key result is that in the long run, firms earn zero economic profit. That doesn’t mean they make no money — it means they earn just enough to cover all costs, including a normal return on their investment. If profits were positive, new firms would enter, supply would increase, price would fall, and profits would be squeezed back to zero. If losses occurred, firms would exit, supply would fall, price would rise, and losses would disappear.
This leads to two important outcomes:
- Productive efficiency: Firms produce at the lowest possible cost per unit (the minimum of the average cost curve).
- Allocative efficiency: The price equals the marginal cost of production — society gets exactly the quantity it values.
In a perfectly competitive market, the demand curve facing a single firm is a horizontal line at the market price. The firm can sell any quantity at that price, but nothing above it. This is why the firm is a price taker.
The revenue and profit picture (with a formula)
For a firm in perfect competition, the market price P is given. The firm’s total revenue is:
TR=P×Q
where Q is the quantity the firm sells. Since P is constant, each additional unit sold adds exactly P to revenue. So the marginal revenue MR is also P:
MR=P
The firm maximises profit by producing the quantity where MR=MC, where MC is marginal cost. Since MR=P, the profit-maximising rule becomes:
P=MC
This is the famous condition for a competitive firm’s equilibrium.
P=MC
- P = market price (constant for the firm)
- MC = marginal cost (the cost of producing one more unit)
The firm’s profit is:
π=TR−TC=(P×Q)−(ATC×Q)=(P−ATC)×Q
where ATC is average total cost. If P>ATC, the firm makes supernormal profit. If P=ATC, profit is zero (normal profit). If P<ATC, the firm incurs a loss.
A diagram in words …
Under perfect competition a firm can sell any quantity at the ruling price, so its demand curve is horizontal — perfectly elastic. …
The correct option is (c) Perfectly elastic.
Under perfect competition there are many firms selling an identical product at a single ruling price. An individual firm is a price-taker — it can sell any quantity at the prevailing price but nothing above it. Therefore the demand curve facing the firm is a horizontal straight line at the ruling price, i.e. perfectly elas …
Showing the 12 most recent of 48 on this concept.
- CBSE 2026Set MARCH1 markQ.Price taking behaviour is the distinguishing characteristic of __________ market.
›Reveal solutionSolution
The blank is filled by Perfect Competition.
Under perfect competition there are so many firms, each producing an identical (homogeneous) product, that no individual firm's output is large enough to affect the market price. Every firm therefore takes the price as given by the market and can only decide how much to produce at that price. This 'price-taking' behaviour is the key characteristic that distinguishes perfect compe …
- CBSE 2026Set ANNUAL1 markQ.Fill in the blank: In the ________ market a firm can enter and exit freely.
›Reveal solutionSolution
Free entry and exit is a feature of the perfectly competitive market.
In a perfectly competitive market, there is free entry and exit of firms — there are no barriers, so firms can enter when there are super-normal profits and leave when there are losses. This ensures that in the long run every firm earns only …
- CBSE 2026Set ANNUAL1 markMCQQ.Write True or False: In a perfectly competitive market firms are price-determinators.(a) True(b) False
›Reveal solutionSolution
False — firms in perfect competition are price-takers, not price-determinators.
Under perfect competition there are very many firms each selling a homogeneous product, and each firm's output is negligible relative to the market. Hence no firm can influence or set the price; it must accept (take) the price determined by overall market demand and supply. So firms are **p …
- CBSE 2026Set ANNUAL1 markMCQQ.In perfect competition, a firm-(a) determines price(b) accept price(c) Both(i) and(ii)(d) None of these(a) determines price(b) accept price(c) Both(i) and(ii)(d) None of these
›Reveal solutionSolution
A firm under perfect competition is a price-TAKER, accepting the market price.
Because a very large number of firms sell an identical (homogeneous) product under perfect competition, no single firm's output decision is large enough relative to the total market to influence the price. Each firm therefore faces a given, fixed market price and simply decides how MUCH to sell at that price — it 'accepts' the price rather than 'determining' it. This is the opposite of Monopoly/Olig …
- CBSE 2025Set MARCH1 markMCQQ.The Equilibrium price in a perfectly competitive market when free entry and exit is allowed.(a) P = Maximum of TR(b) P = Minimum of TR(c) P = Maximum of AC(d) P = Minimum of AC
›Reveal solutionSolution
With free entry and exit, long-run equilibrium price equals the minimum of the average cost curve — option (d).
…
- CBSE 2025Set MARCH1 markQ.Fill in the blank by choosing correct answer from the bracket (Financial, Government, RBI, Perfect competition, Product, Private): Price taking behaviour is the distinguishing characteristic of __________ market.
›Reveal solutionSolution
The blank is filled by 'Perfect competition'.
A perfectly competitive market has a large number of buyers and sellers, a homogeneous product, and free entry and exit. Because each firm is very small relative to the whole market, no single firm can affect the price by changing its own output. Every firm therefore takes the market-determined …
- CBSE 2025Set ANNUAL1 markMCQQ.Market situation where there is only one buyer is (A) Monopoly (B) Monopsony (C) Duopoly (D) None of these
›Reveal solutionSolution
A market with a single buyer is a monopsony, so the answer is (B).
Market structures are classified by the number of buyers and sellers. Monopoly means a single seller; duopoly means two sellers. When there is only one buyer facing many sellers, the market is a monopsony — the lone buyer has buying (monopsony) power over price. A common real example is a single large employer in a local labour market. Hence the situation with only one buyer is monopsony. (Non-compet …
- CBSE 2025Set ANNUAL1 markMCQQ.In which market is product differentiation found? (A) Pure competition (B) Perfect competition (C) Monopoly (D) Monopolistic competition
›Reveal solutionSolution
Product differentiation is found in monopolistic competition, so the answer is (D).
In perfect and pure competition, all firms sell an identical (homogeneous) product, so there is no product differentiation. In monopoly there is a single firm and a single product, so differentiation does not arise either. Monopolistic competition has many firms selling closely related but differentiated products — distinguished by brand name, design, packaging, quality or advertising (for example, different brands of toothpaste or soap). This product differentiation gives each firm some control over its pr …
- CBSE 2025Set ANNUAL1 markMCQQ.The concept of monopolistic competition is given by (A) Hicks (B) Chamberlin (C) Mrs. Robinson (D) Samuelson
›Reveal solutionSolution
The concept of monopolistic competition was given by Chamberlin, so the answer is (B).
Edward H. Chamberlin propounded the theory of monopolistic competition in his book 'The Theory of Monopolistic Competition' (1933), analysing markets with many firms selling differentiated products. Around the same time, Joan Robinson developed the related theory of 'imperfect competition', but the specific term and framework of monopolistic competition are credited to Chamberlin. Hicks and Samuelson are associated with o …
- CBSE 2025Set ANNUAL1 markMCQQ.What is the type of demand curve of monopoly? (A) Inelastic (B) Elastic (C) Perfectly elastic (D) Perfectly inelastic
›Reveal solutionSolution
A monopoly faces a downward-sloping, relatively elastic demand curve, so the answer is (B) Elastic.
Under monopoly there is a single firm, so the firm's demand curve is the entire market demand curve, which slopes downward from left to right. To sell more, the monopolist must lower the price, so the curve is not perfectly elastic (a horizontal line, which belongs to perfect competition) and not perfectly inelastic (a vertical line). It is an ordinary downward-sloping demand curve, i.e. elastic/sloping rather than a straight horizontal or vertical line. Among the given …
- CBSE 2025Set ANNUAL1 markMCQQ.The single most distinguishing characteristic of perfect competition is - (A) Goods discrimination (B) Price taking behaviour of a firm (C) Excess profit (D) Price rigidity
›Reveal solutionSolution
The defining feature of perfect competition is that firms are price-takers, so (B) is correct.
In the RBSE/CBSE Class-12 chapter on the firm under perfect competition, the market has a very large number of buyers and sellers trading a homogeneous (identical) product, with free entry and exit and perfect information. The combined result of these conditions is that no individual firm can affect the market price — the price is set by overall market demand and supply, and each firm must take that price as given.
…
- CBSE 2025Set ANNUAL1 markQ.Fill in the blank: Free entry and exit of the firm implies that the market price will always be equal to ________.
›Reveal solutionSolution
The blank is the minimum of average cost — free entry and exit pushes long-run price to minimum AC, leaving only normal profit.
In the RBSE/CBSE Class-12 chapter on the firm under perfect competition, free entry and exit is a key feature. If existing firms earn super-normal profit, new firms enter, raising supply and lowering price; if firms make losses, some exit, reducing supply and raising price. This process continues until every firm earns only normal profit (zero economic profit).
…
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