Monopoly (Price and Output Determination)

1) Meaning: what is a monopoly?

A monopoly is a market structure where there is a single seller of a product that has no close substitutes, and where entry is blocked by significant barriers.

A monopolist is a price maker (or price setter) in the sense that it chooses price-output combination subject to the market demand curve. However, it cannot choose price and quantity independently—choosing one determines the other through demand.

2) Key features / assumptions

Single firm constitutes the industry.
Downward sloping market demand curve faced by the firm.
High barriers to entry (legal, technological, strategic).
No close substitutes for the product.
Monopolist aims to maximize profit (standard assumption).

3) Sources of monopoly power (barriers to entry)

Monopoly arises due to barriers such as:

3.1 Legal barriers

patents, copyrights,
exclusive licenses,
government franchise.

3.2 Control over key resource

exclusive ownership of essential input.

3.3 Natural monopoly

occurs when economies of scale are so strong that one firm can supply the entire market at lower cost than multiple firms.
typical in utilities (water, electricity distribution) due to high fixed costs and declining LRAC over relevant output range.

3.4 Technological barriers

high R&D requirements, complex know-how.

3.5 Strategic barriers

predatory pricing, limit pricing, capacity expansion, etc.

CUET note: Natural monopoly is a common conceptual MCQ.

4) Demand, AR and MR under monopoly

Because a monopolist faces the market demand curve:

Average Revenue (AR) curve is the demand curve: $AR = P(Q)$
Total Revenue (TR): $TR(Q) = P(Q)\cdot Q$
Marginal Revenue (MR): $MR(Q) = \frac{dTR}{dQ}$

4.1 Key property: MR lies below AR

For a downward sloping demand:

To sell one more unit, monopolist must lower price on all units (in uniform pricing).
Hence MR < P.

For linear demand:

MR has the same intercept as AR and twice the slope. (Important for quick numericals.)