Introduction to Supply, Demand, and Competitive Equilibrium in Microeconomics

Introduction to Supply, Demand, and the Benchmark Competitive Equilibrium

Perfectly Competitive Markets

Microeconomics often begins with the study of perfectly competitive markets, which serve as a benchmark for understanding market behavior and outcomes.

• Definition: A perfectly competitive market is one in which all sellers offer an identical good or service, and no individual buyer or seller is large enough to influence the market price.

• Key Features:

  • Many buyers and sellers

  • Identical products

  • Free entry and exit

  • Price takers: Each participant accepts the market price as given

• Example: Agricultural markets, such as wheat or corn, often approximate perfect competition.

Demand Curve

The demand curve is a fundamental concept that illustrates how the quantity demanded by buyers varies with the market price.

• Definition: The demand curve plots the relationship between the market price and the quantity of a good demanded by buyers.

• Law of Demand: As price decreases, quantity demanded generally increases, holding all else equal.

• Equation Example: $Q_D = a - bP$ where $Q_D$ is quantity demanded, $P$ is price, and $a, b$ are constants.

• Graphical Representation: The demand curve typically slopes downward from left to right.

Supply Curve

The supply curve shows how the quantity supplied by sellers changes as the market price changes.

• Definition: The supply curve plots the relationship between the market price and the quantity of a good supplied by sellers.

• Law of Supply: As price increases, quantity supplied generally increases, holding all else equal.

• Equation Example: $Q_S = c + dP$ where $Q_S$ is quantity supplied, $P$ is price, and $c, d$ are constants.

• Graphical Representation: The supply curve typically slopes upward from left to right.

Competitive Equilibrium

Competitive equilibrium is the point at which the market price balances the quantity demanded and the quantity supplied.

• Definition: The competitive equilibrium price is the price at which quantity demanded equals quantity supplied.

• Equation: Set $Q_D = Q_S$ and solve for $P$ to find the equilibrium price.

• Example: If $Q_D = 100 - 2P$ and $Q_S = 20 + 3P$, set $100 - 2P = 20 + 3P$ to solve for $P$.

Market Failures Due to Price Controls

When prices are not allowed to fluctuate freely, markets may fail to reach equilibrium, resulting in shortages or surpluses.

• Price Ceiling: A legal maximum price can lead to excess demand (shortage).

• Price Floor: A legal minimum price can lead to excess supply (surplus).

• Example: Rent control (price ceiling) may cause housing shortages.

Markets

Definition and Structure of Markets

Markets are the foundational institutions in microeconomics where goods and services are exchanged.

• Definition: A market is a group of economic agents trading a good or service, governed by rules and arrangements for trading.

• Market Price: The market price is the price at which buyers and sellers conduct transactions.

• Types of Markets:

  • Physical markets (e.g., farmers' markets)

  • Virtual markets (e.g., stock exchanges)

Perfect Competition in Markets

Perfect competition is a theoretical market structure that helps economists analyze real-world markets.

• Characteristics:

  • Many identical sellers and buyers

  • Uniform market price

  • No single agent can influence the price

• Example: Commodity markets such as those for eggs, wheat, or oil.

Application: Price Differences in Markets

Microeconomics uses supply and demand analysis to explain price differences, such as why brown eggs cost more than white eggs.

• Demand Side: Perceptions of health or organic quality may increase demand for brown eggs.

• Supply Side: Brown eggs are more expensive to produce because hens that lay brown eggs are larger and require more food.

• Result: The higher production cost shifts the supply curve for brown eggs to the left, resulting in a higher equilibrium price.

• Example: Despite consumer beliefs, nutrient levels are not significantly different between white and brown eggs.

Additional info: These notes expand on the brief points in the images, providing definitions, examples, and equations for key microeconomic concepts.