# A student uses an electric kettle to heat water. Explain why the efficiency of the kettle can never reach 100%, and describe ONE way in which the design of the kettle could be improved to increase its efficiency.

> Eduqas A-Level Physics — 1.3 Energy concepts · Explain · 5 marks

> An electric kettle is designed to transfer electrical energy to heat the water inside it. In practice, some energy is also transferred to the surrounding air and to the kettle's outer casing.

## Mark scheme (5 marks)

1. Energy cannot be created or destroyed (conservation of energy), so the total energy input equals the total energy output
2. Some energy is transferred to the surroundings / outer casing as waste energy transfer (e.g. heat to the air)
3. Because some energy is wasted, the useful output energy transfer is always less than the total input energy
4. Named design improvement — e.g. adding thermal insulation to the outer casing / using insulating materials
5. Explanation of how the improvement reduces waste energy transfer / increases the proportion of energy used to heat the water

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level 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-student-uses-an-electric-kettle-9b9dbb7d) · Published by Druglandscape Ltd.