A Level Economics AQA Practice Exam 2026 – The All-in-One Guide to Mastering A Level Success!

Positive externalities occur when the actions of individuals or firms have beneficial effects on third parties who are not directly involved in the transaction. In the context of public goods, these benefits spill over to consumers and society at large. For example, when someone gets vaccinated, it not only protects them but also contributes to herd immunity, thereby protecting others in the community.

This understanding highlights the significance of positive externalities in promoting social welfare, as they indicate that the full benefits of certain actions or goods are not captured by the market. In contrast, other choices focus on aspects such as costs or negative impacts, which are not aligned with the definition of positive externalities.