# Explain why metals are good conductors of electricity, and why increasing the temperature of a metal wire causes its resistance to increase.

> WJEC A-Level Physics (Wales) — 2.1 Conduction and resistance · Explain · 5 marks

> Metals such as copper are widely used in electrical wiring because of their low resistance. However, engineers must consider that the resistance of a metal wire changes with temperature.

## Mark scheme (5 marks)

1. Metals contain free (delocalised) electrons that can move through the material
2. These free electrons carry charge through the metal, allowing current to flow
3. When temperature increases, the metal ions vibrate more (with greater amplitude / more vigorously)
4. The more vigorously vibrating ions obstruct / collide more frequently with the free electrons
5. This increased obstruction makes it harder for charge to flow, so resistance increases

## Key terms

- [resistance](https://www.gradenine.co.uk/glossary/resistance)
- [conductor](https://www.gradenine.co.uk/glossary/conductor)

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](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/explain-why-metals-are-good-conductors-aeeca903) · Published by Druglandscape Ltd.