# A toaster has a metal casing and is connected to the mains electricity supply using a three-core cable. The live wire inside the toaster accidentally touches the metal casing, creating a short circuit. Explain how the earth wire and fuse work together to protect the user from electric shock.

> Pearson Edexcel International GCSE Physics (4PH1) — 2.1 Mains electricity · Explain · 4 marks

## Mark scheme (4 marks)

1. The earth wire provides a low resistance path for current to flow from the metal casing to earth
2. A large/surge of current flows through the earth wire
3. The large current causes the fuse to melt/blow
4. The circuit is broken/disconnected, preventing current from reaching the metal casing and protecting the user from electric shock

## Key terms

- [earth wire](https://www.gradenine.co.uk/glossary/earth-wire)
- [fuse](https://www.gradenine.co.uk/glossary/fuse)
- [live wire](https://www.gradenine.co.uk/glossary/live-wire)
- [short circuit](https://www.gradenine.co.uk/glossary/short-circuit)
- [mains electricity](https://www.gradenine.co.uk/glossary/mains-electricity)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](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-toaster-has-a-metal-casing-875e8d20) · Published by Druglandscape Ltd.