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.
These resources will be removed by end of Summer Term 2025.
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.
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
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.
To help you plan your year 11 physics lesson on: Power of an appliance or electric circuit, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 11 physics lesson on: Power of an appliance or electric circuit, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 4 physics lessons from the Mains electricity unit, dive into the full secondary physics curriculum, or learn more about lesson planning.
Licence
Starter quiz
6 Questions

