# A household has two lighting options: traditional filament bulbs with a power-rating of 60 W, or LED bulbs with a power-rating of 8 W, both producing the same brightness. Explain why replacing filament bulbs with LED bulbs reduces the number of kilowatt-hours used by the household each month.

> Eduqas GCSE Physics — 1.4 Domestic electricity · Explain · 4 marks

## Mark scheme (4 marks)

1. The kilowatt-hour is a unit of energy used to measure domestic energy consumption
2. Power-rating is the rate at which energy is transferred / LED bulbs transfer energy at a lower rate
3. More energy from a filament bulb is wasted (e.g. as heat/thermal energy) rather than transferred as useful light
4. Because the LED has a lower power-rating, fewer kilowatt-hours are used over the same period of time

## Key terms

- [kilowatt-hour](https://www.gradenine.co.uk/glossary/kilowatt-hour)
- [power-rating](https://www.gradenine.co.uk/glossary/power-rating)

## 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-household-has-two-lighting-options-5b19950b) · Published by Druglandscape Ltd.