Demand and the Law of Demand Notes

Demand and the Law of Demand

  • Definition of Demand: The amount of a good or service that consumers are willing and able to buy, reflecting the relationship between price and quantity.
  • Key Conditions for Demand: Includes both the ability and the desire to purchase goods.

Understanding Demand

  • Price vs. Quantity Demanded: The quantity demanded moves inversely to price.
  • When price increases, quantity demanded decreases.
  • When price decreases, quantity demanded increases.

Demand Schedule


  • Purpose: Helps businesses set prices to maximize revenue.

  • Example Schedule (Market Demand Schedule for Soda):

Price ($)Quantity Demanded
0.25890
0.50500
0.75480
1.00470
1.25410
1.50350
1.75280
2.00240
2.25200
2.50150
2.75100

Demand Curve

  • Definition: A graphical representation of the demand schedule showing the relationship between price and quantity demanded.
  • Law of Demand: Reflects that the demand curve slopes downwards, indicating that higher prices lead to lower quantities demanded.

Factors Influencing Demand

  • 1. Income Effect: A change in consumer income affects how much of a good is bought.
  • 2. Substitution Effect: If the price of a good rises, consumers may switch to cheaper substitutes.
  • Example: If steak becomes more expensive, consumers may buy more chicken.
  • 3. Diminishing Marginal Utility: Successive units of a product provide less satisfaction; hence, consumers will only buy more if prices decrease.

Demand Shift vs. Movement

  • Movement Along the Curve: Caused by changes in the price of the good.
  • Shift of the Demand Curve: Caused by changes in determinants of demand such as:
  • Consumer preferences
  • Market size
  • Income levels
  • Prices of related goods
  • Consumer expectations
  • Right Shift: Indicates an increase in demand.
  • Left Shift: Indicates a decrease in demand.

Elasticity of Demand

  • Definition: Measures how the quantity demanded responds to price changes.
  • Types:
  • Elastic Demand: A small change in price leads to a large change in quantity demanded.
  • Inelastic Demand: Quantity demanded changes little when the price changes.

Summary of Key Points

  • Demand is influenced by price changes, shifting determinants, and consumer behavior. Understanding these concepts is essential for analyzing market dynamics and making informed economic decisions.