# Power of an appliance or electric circuit

I can describe how the power of an appliance or electric circuit depends on current and potential difference.

# Power of an appliance or electric circuit

I can describe how the power of an appliance or electric circuit depends on current and potential difference.

## Lesson details

### Key learning points

- Power is the amount of energy transferred per second and is measured in watts (W).
- Power can be calculated using the equation: power = current × potential difference (P = I V).
- At a constant p.d., a larger electric current transfers energy more quickly than a smaller current.
- Domestic appliances plugged into the mains supply in the UK have a p.d. of 230 V across them.
- The fuse with the smallest rating for the required current (calculated using the equation: P = I² R) should be used.

### Common misconception

Pupils often use the terms power and energy interchangeably.

Use concrete examples to show pupils that a greater power transfers energy more quickly.

### Keywords

Power - the amount of energy transferred each second

Watts (W) - the unit of power; equal to the number of joules of energy transferred each second

Kilowatts (kW) - a unit of power; 1 kilowatt is equal to 1000 watts

Fuse - a thin wire that melts when a dangerously large current flows through it

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Video

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