Lecture Notes: Chapter 11 – Perfect Competition
Based on Microeconomics: Canada in the Global Environment (11th Edition)
Introduction
Perfect competition is a theoretical market structure that serves as a benchmark for evaluating the
efficiency of real-world markets. In this chapter, we define perfect competition, examine how
firms make output decisions, and analyze how price and output are determined in both the short
and long run. We also explore the role of technological change and explain why perfect
competition leads to an efficient allocation of resources. Though real markets rarely meet all the
conditions of perfect competition, understanding this model helps explain important economic
behaviors and outcomes.
1. Defining Perfect Competition
Characteristics of Perfect Competition
A perfectly competitive market has the following features:
1. Many buyers and sellers – Each is small relative to the market and cannot influence
price.
2. Identical products – Goods are perfect substitutes (e.g., wheat, corn).
3. No barriers to entry or exit – Firms can freely enter or leave the market.
4. Perfect information – All buyers and sellers know prices and product quality.
5. Price takers – Firms and consumers accept the market price as given.
Example:
Agricultural markets often come close to perfect competition. A farmer selling wheat has no
influence on the market price and must sell at the prevailing rate.
2. A Firm’s Output Decision in Perfect Competition
Revenue in Perfect Competition
In perfect competition, a firm is a price taker: the price is set by the market and cannot be
influenced by individual producers.
Total Revenue (TR):
, Average Revenue (AR):
Marginal Revenue (MR):
Since each additional unit sold brings the same price, MR = P = AR.
Profit-Maximizing Rule
A perfectly competitive firm maximizes profit by producing the quantity at which:
Where:
MR = marginal revenue (equal to price in perfect competition)
MC = marginal cost
If MR > MC, the firm can increase profit by producing more.
If MR < MC, the firm should reduce output.
Graph Description:
X-axis: Quantity of output
Y-axis: Price and cost
Horizontal MR (price) line intersects the U-shaped MC curve at the profit-maximizing
quantity.
Example:
If the market price of strawberries is $4/kg, a farm will produce where its marginal cost = $4.
3. Short-Run Price and Output Determination
Based on Microeconomics: Canada in the Global Environment (11th Edition)
Introduction
Perfect competition is a theoretical market structure that serves as a benchmark for evaluating the
efficiency of real-world markets. In this chapter, we define perfect competition, examine how
firms make output decisions, and analyze how price and output are determined in both the short
and long run. We also explore the role of technological change and explain why perfect
competition leads to an efficient allocation of resources. Though real markets rarely meet all the
conditions of perfect competition, understanding this model helps explain important economic
behaviors and outcomes.
1. Defining Perfect Competition
Characteristics of Perfect Competition
A perfectly competitive market has the following features:
1. Many buyers and sellers – Each is small relative to the market and cannot influence
price.
2. Identical products – Goods are perfect substitutes (e.g., wheat, corn).
3. No barriers to entry or exit – Firms can freely enter or leave the market.
4. Perfect information – All buyers and sellers know prices and product quality.
5. Price takers – Firms and consumers accept the market price as given.
Example:
Agricultural markets often come close to perfect competition. A farmer selling wheat has no
influence on the market price and must sell at the prevailing rate.
2. A Firm’s Output Decision in Perfect Competition
Revenue in Perfect Competition
In perfect competition, a firm is a price taker: the price is set by the market and cannot be
influenced by individual producers.
Total Revenue (TR):
, Average Revenue (AR):
Marginal Revenue (MR):
Since each additional unit sold brings the same price, MR = P = AR.
Profit-Maximizing Rule
A perfectly competitive firm maximizes profit by producing the quantity at which:
Where:
MR = marginal revenue (equal to price in perfect competition)
MC = marginal cost
If MR > MC, the firm can increase profit by producing more.
If MR < MC, the firm should reduce output.
Graph Description:
X-axis: Quantity of output
Y-axis: Price and cost
Horizontal MR (price) line intersects the U-shaped MC curve at the profit-maximizing
quantity.
Example:
If the market price of strawberries is $4/kg, a farm will produce where its marginal cost = $4.
3. Short-Run Price and Output Determination
