Externality Diagrams and Welfare Loss

This page presents diagrams illustrating the effects of positive and negative externalities on consumption and production, as well as the concept of welfare loss.

Positive Externality Diagrams

The diagrams for positive externalities in consumption and production show:

• MSB (Marginal Social Benefit) curve above MPB (Marginal Private Benefit) curve for consumption
• MSB curve above MPC (Marginal Private Cost) curve for production

Highlight: In positive externality scenarios, the socially optimal quantity (Q2) is greater than the market equilibrium quantity (Q1).

Negative Externality Diagrams

The diagrams for negative externalities in consumption and production illustrate:

• MSC (Marginal Social Cost) curve above MPB curve for consumption
• MSC curve above MPC curve for production

Highlight: In negative externality scenarios, the socially optimal quantity (Q2) is less than the market equilibrium quantity (Q1).

Welfare Loss and Social Optimum

Definition: Welfare loss represents the economic inefficiency caused by externalities, shown as the shaded area in the diagrams.

Highlight: The welfare loss always points towards the social optimum, where MSB equals MSC.

Vocabulary: Social optimum is the point where marginal social benefit equals marginal social cost, representing the most efficient level of production or consumption for society.

These diagrams help visualize the concepts of positive externalities in Economics and negative externalities and resource misallocation, providing a clear representation of how externalities affect market outcomes and social welfare.