Mains electricity
I can compare the power of different appliances and work out how much they cost to use.
Mains electricity
I can compare the power of different appliances and work out how much they cost to use.
Lesson details
Key learning points
- Electrical appliances and devices use different amounts of energy each second, as indicated by their power rating.
- Power is a measure of the amount of energy used by or supplied to a device in one second.
- Power is measured in watts (W).
- Multiplying power of a device in kilowatts (kW) by time in hours (h) gives us the energy used in kilowatt–hours (kWh).
- Electricity bills are based on the amount of energy units used; 1 unit of energy is equal to 1 kWh.
Common misconception
Most pupils do not discriminate sufficiently between current, voltage, energy and power.
Provide pupils with opportunities to calculate energy usage with appliances that have different power ratings and are used for different lengths of time.
Keywords
Power - the amount of energy transferred every second
Watts (W) - the unit of power
Kilowatts (kW) - a larger unit of power; 1 kW = 1000 W
Joules (J) - the unit of energy
Kilowatt–hours (kWh) - the unit of energy usage; 1 kWh = 1 unit of energy used
Equipment
Wattmeter (joulemeter) if available for demonstration and a range of devices to test.
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
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).
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