# A student uses an electric kettle to heat water for a hot drink. The kettle is designed to transfer electrical energy to the water. Explain what happens to the energy in this system, including reference to useful energy transfer, waste energy transfer, and the conservation of energy.

> Edexcel GCSE Physics (1PH0) — 3.1 Conservation of energy · Explain · 4 marks

> An electric kettle is plugged into the mains and switched on. The kettle heats the water inside it. The outside of the kettle also becomes warm to the touch, and a humming sound can be heard whilst it operates.

## Mark scheme (4 marks)

1. The useful energy transfer is electrical energy being transferred to thermal energy (heat) in the water.
2. Some energy is wasted — transferred as heat to the surroundings (e.g. through the warm outer casing) and/or as sound.
3. The total energy output (useful + waste) equals the total electrical energy input — energy is conserved.
4. Energy cannot be created or destroyed, only transferred, stored or dissipated — the total energy of the closed system remains constant.

## 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)
- [conservation of energy](https://www.gradenine.co.uk/glossary/conservation-of-energy)

## Related

- [Revision notes for Edexcel GCSE Physics (1PH0)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-uses-an-electric-kettle-ff7b2536) · Published by Druglandscape Ltd.