# A hydroelectric power station uses water held in a reservoir at the top of a hill to generate electricity. Explain how energy is transferred from the water in the reservoir to produce electricity, and state one reason why hydroelectric power is considered a renewable energy resource.

> WJEC GCSE Physics (Wales) — 1.2 Generating electricity · Explain · 4 marks

## Mark scheme (4 marks)

1. The water in the reservoir has gravitational potential energy (because it is raised/at height)
2. As the water falls/flows down, gravitational potential energy is transferred to kinetic energy
3. The moving/flowing water turns a turbine (which drives/is connected to a generator)
4. Hydroelectric power is renewable because the water supply can be replenished (e.g. by rainfall) whilst it is being used / it is not a finite resource

## Key terms

- [renewable energy resource](https://www.gradenine.co.uk/glossary/renewable-energy-resource)

## Related

- [Revision notes for WJEC GCSE 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/a-hydroelectric-power-station-uses-water-73435a90) · Published by Druglandscape Ltd.