Price Mechanism | A-Level Economics Notes
These revision notes cover everything you need to know about the Price Mechanism for A-Level Economics. They're designed for students studying AQA A-Level Economics, Edexcel A-Level Economics, and Edexcel International A-Level Economics. Written by Jaisul Naik, UCL Economics graduate and A-Level Economics tutor since 2017.
Increase in demand
- The diagram below shows an increase in demand, which can be caused by factors like an increase in income.
- At the old market price p1, there is an excess demand.
- Firms notice this through market signals as they may see larger queues of customers waiting to be served,
- Firms respond by raising prices.
- The new market price p2 is higher so firms are incentivised to expand their supply to make higher profits, whilst consumers are incentivised to contract their demand.
- The market clears at the new equilibrium quantity of q2 where excess demand has been rationed.

Decrease in demand
- The diagram shows a decrease in demand.
- At the old price p1, there is an excess supply.
- This information is signalled to firms, for example they may empty shops.
- Firms respond by decreasing prices.
- This incentivises firms to c0nsumers to expand demand and it incentivises firms to contract their supply due to lower profits.
- Overall, the market clears at a new equilibrium at q2, where the excess supply is rationed away.

Decrease in supply
- The diagram shows a decrease in supply.
- At the old market price p1, there is an excess demand.
- This information gets signalled to producers; they may see an increase in the number of customers waiting.
- Firms respond by increasing prices.
- A higher prices incentivises producers to expand their supply due to higher profit and it incentivises consumers to contract their demand.
- Overall, the market clears at a new equilibrium at q2, where the excess demand is rationed away.

Increase in supply
- The diagram shows an increase in supply.
- At the old price p1, there is an excess supply.
- This information is signalled to firms, for example they may empty shops.
- Firms respond by decreasing prices.
- This incentivises firms to c0nsumers to expand demand and it incentivises firms to contract their supply due to lower profits.
- Overall, the market clears at a new equilibrium at q2, where the excess supply is rationed away.

Summary questions
- How does the price mechanism respond to
- an increase in demand
- a decrease in demand
- a decrease in supply
- an increase in supply
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