# A student rubs a plastic rod with a woollen cloth. The plastic rod becomes negatively charged. Explain why the rod becomes negatively charged and describe what charge is left on the woollen cloth. Include in your answer what would happen if a charged plastic rod were brought close to, but not touching, a second negatively charged rod.

> Edexcel A-Level Physics (9PH0) — 11.1 Radioactivity, fission and fusion · Explain · 5 marks

## Mark scheme (5 marks)

1. Electrons are transferred from the woollen cloth to the plastic rod (by friction / during rubbing)
2. The plastic rod gains electrons, giving it a negative static charge
3. The woollen cloth loses electrons, leaving it with a positive static charge
4. The two negatively charged rods have like charges, so they repel each other
5. The repulsive force is a non-contact (electrostatic) force, felt even though the rods are not touching

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](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-rubs-a-plastic-rod-b91a8913) · Published by Druglandscape Ltd.