# A fuel tanker delivers petrol through a hose to an underground storage tank at a petrol station. As the fuel flows through the hose, a static charge builds up. Explain why this static charge builds up and why it is dangerous, and describe how earthing the hose prevents the danger.

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

> Petrol is an insulating liquid. As it flows rapidly through a rubber hose, electrons are transferred between the fuel and the hose.

## Mark scheme (5 marks)

1. As the fuel flows through the hose, friction causes electrons to be transferred from one material to the other
2. Because the hose is an insulator, the electrons cannot flow away, so a static charge builds up on the hose
3. When the charge becomes large enough, a spark jumps through the air to balance the charges
4. The spark could ignite the petrol vapour, causing a fire or explosion
5. Earthing provides a low resistance path for electrons to flow to the Earth, so excess charge is removed and cannot build up to a level that causes a spark

## Key terms

- [static charge](https://www.gradenine.co.uk/glossary/static-charge)
- [earthing](https://www.gradenine.co.uk/glossary/earthing)

## 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-fuel-tanker-delivers-petrol-through-bdf2129f) · Published by Druglandscape Ltd.