# A wind turbine generates electricity. Some of the energy input to the turbine is wasted. Explain how the efficiency of the wind turbine can be calculated, and describe TWO ways in which the efficiency of the turbine could be increased.

> Edexcel A-Level Physics (9PH0) — 3.1 Charge and current · Explain · 5 marks

> A wind turbine converts kinetic energy from moving air into electrical energy. Engineers monitor the energy input and the useful energy output of the turbine. Not all of the input energy is transferred usefully — some is wasted as heat and sound.

## Mark scheme (5 marks)

1. Efficiency is the ratio of useful output energy to total input energy
2. Efficiency can never exceed 1 (or 100%) due to conservation of energy
3. Lubrication of moving parts reduces friction
4. Lubrication reduces waste heat energy transferred to the surroundings, so more energy is usefully transferred as electricity
5. Thermal insulation reduces the rate of heat loss to the surroundings / waste heat energy can be recycled and used as an input

## Key terms

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

## 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-wind-turbine-generates-electricity-some-bf7cb2d6) · Published by Druglandscape Ltd.