# AS AQA Phys Unit 1- Electrical Energy and Power

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- Created by: Jessica Parkes
- Created on: 29-03-13 17:33

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Power

Power is defined as **the rate of transfer of energy**. It is measured in watts (W), where 1W = 1 joule per second i.e. P = E / t.

In electrical circuits: P = VI

This is because;

1) Potential difference (V) is defined as the energy transferred per coulomb.

2) Current (I) is defined as the number of coulombs transferred per second

Therefore, p.d. x current is energy transferred per second i.e. power

The definition of resistance shows: V = IR

If this is combined with the previous equation different methods of calculating power can result;

**P = VI,**…

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