# A wind turbine transfers energy from the wind to electrical energy. Explain why the wind turbine cannot be 100% efficient, and describe what happens to the energy that is not usefully transferred.

> WJEC GCSE Physics (Wales) — 1.6 Distance, speed and acceleration · Explain · 4 marks

> A wind turbine is connected to the National Grid. Its power rating is 2 MW. Engineers note that a significant proportion of the input energy is lost during operation.

## Mark scheme (4 marks)

1. The efficiency can never exceed 100% / 1 due to the conservation of energy — energy cannot be created
2. Some energy is transferred as waste energy / not all energy transfer serves the purpose of the system
3. Waste energy is transferred as thermal energy / heat due to friction in the moving parts
4. Waste energy is dissipated / spread out to the surroundings and is no longer useful

## 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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