# A family is trying to reduce their electricity bill. They compare two electric heaters that produce the same amount of heat. Heater A has a power-rating of 3 kW and Heater B has a power-rating of 2 kW. Explain why choosing Heater B would reduce the family's electricity costs, referring to the kilowatt-hour in your answer.

> Eduqas GCSE Physics — 1.4 Domestic electricity · Explain · 4 marks

> Both heaters are used for 4 hours each day.

## Mark scheme (4 marks)

1. The kilowatt-hour is the unit used to measure domestic energy consumption
2. The number of kilowatt-hours used depends on the power-rating of the appliance (and the time it is used)
3. Heater B has a lower power-rating (2 kW) so it uses fewer kilowatt-hours than Heater A (3 kW) in the same time period
4. Because fewer kilowatt-hours are used, the cost of electricity is lower / the electricity bill is reduced

## Key terms

- [power-rating](https://www.gradenine.co.uk/glossary/power-rating)
- [kilowatt-hour](https://www.gradenine.co.uk/glossary/kilowatt-hour)

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-family-is-trying-to-reduce-da0dccdd) · Published by Druglandscape Ltd.