# A washing machine transfers electrical energy when it is running. Explain how improving the efficiency of the washing machine reduces waste energy transfer.

> WJEC GCSE Physics (Wales) — 1.3 Making use of energy · Explain · 4 marks

> A washing machine has a power rating of 2 kW. Much of the electrical energy input is lost as heat and sound rather than being used to wash the clothes.

## Mark scheme (4 marks)

1. Efficiency is the ratio of useful output energy transfer to total energy input
2. Waste energy transfer is energy transferred to a form that does not directly serve the purpose of the system (e.g. heat/sound in the washing machine)
3. Improving efficiency means a greater proportion of the total input energy becomes useful energy transfer
4. So the waste energy transfer (heat/sound) is reduced because energy cannot be created or destroyed (conservation of energy)

## Key terms

- [efficiency](https://www.gradenine.co.uk/glossary/efficiency)
- [waste energy transfer](https://www.gradenine.co.uk/glossary/waste-energy-transfer)

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-washing-machine-transfers-electrical-energy-71acf728) · Published by Druglandscape Ltd.