# A student plugs a kettle into a mains socket at home. The kettle has a metal casing and is connected to the live wire, the neutral wire, and the earth wire. Explain why the kettle has three pins on its plug rather than two.

> Eduqas GCSE Physics — 7.4 Domestic uses and safety · Explain · 4 marks

> Mains electricity in the UK is supplied at 230 V. The plug of the kettle has a live pin, a neutral pin, and an earth pin.

## Mark scheme (4 marks)

1. The live wire carries the alternating current / voltage to the appliance
2. The neutral wire completes the circuit / provides the return path for the current
3. The earth wire is a safety wire connected to the metal casing
4. If a fault occurs and the casing becomes live, current flows through the earth wire, which blows the fuse / trips the circuit breaker, making the appliance safe

## Key terms

- [live wire](https://www.gradenine.co.uk/glossary/live-wire)
- [neutral wire](https://www.gradenine.co.uk/glossary/neutral-wire)
- [earth wire](https://www.gradenine.co.uk/glossary/earth-wire)
- [metal casing](https://www.gradenine.co.uk/glossary/metal-casing)

## 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-student-plugs-a-kettle-into-ed9515ad) · Published by Druglandscape Ltd.