# A kettle is used to heat water. Explain what happens to the energy stored in the electrical supply during this process, including reference to any useful energy transfer and waste energy transfer that occurs.

> OCR GCSE Physics A: Gateway Science (J249) — P5.1 Energy stores and transfers · Explain · 4 marks

> A student notices that the outside of a kettle feels warm to the touch after it has finished boiling. She also hears a rumbling sound as the water heats up.

## Mark scheme (4 marks)

1. Electrical energy is transferred to thermal energy in the water (useful energy transfer).
2. Energy is also transferred to the surroundings as heat through the kettle's walls (waste energy transfer).
3. Energy is also transferred as sound (waste energy transfer), e.g. the rumbling noise heard during boiling.
4. The total energy input equals the sum of all useful and waste energy transfers, in accordance with the conservation of energy.

## Key terms

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

## Related

- [Revision notes for OCR GCSE Physics A: Gateway Science (J249)](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-kettle-is-used-to-heat-728257f7) · Published by Druglandscape Ltd.