# A laptop computer is connected to the mains electricity supply whilst being used to play a video. Explain why the laptop is not 100% efficient, and describe one way in which the efficiency of the laptop could be improved.

> Eduqas GCSE Physics — 1.6 Distance, speed and acceleration · Explain · 4 marks

> A laptop transfers electrical energy from the mains supply. Its fan runs continuously to prevent overheating during use.

## Mark scheme (4 marks)

1. The laptop produces waste energy transfer(s) / not all energy transferred is useful
2. Named waste energy transfer — e.g. thermal/heat energy transferred to surroundings (from the components/fan)
3. Conservation of energy means total energy output equals total energy input, so if some is wasted the useful output must be less than the input / efficiency cannot exceed 1 (100%)
4. Efficiency could be improved by lubrication (of moving parts / fan) OR by using components that produce less waste thermal energy (e.g. lower-resistance components) — reducing waste energy transfer

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Physics](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-laptop-computer-is-connected-to-eeaba3f4) · Published by Druglandscape Ltd.