# A metal cooking pot is painted matt black on the outside. Explain why this coating is more effective at keeping food warm than a shiny silver coating would be.

> AQA GCSE Physics (8463) — 4.6.3 Black body radiation (Phys only) · Explain · 4 marks

> A manufacturer claims that painting the outside of a cooking pot matt black helps food stay warmer for longer after cooking.

## Mark scheme (4 marks)

1. A black body / matt black surface is a better emitter of infrared radiation than a shiny/silver surface
2. The shiny/silver surface emits less infrared radiation (in a given time)
3. So the matt black pot loses energy (by radiation) at a faster rate / the shiny pot loses energy more slowly
4. Therefore the shiny/silver coating is more effective at keeping food warm because less energy is transferred to the surroundings

## Related

- [Revision notes for AQA GCSE Physics (8463)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-metal-cooking-pot-is-painted-536aeccd) · Published by Druglandscape Ltd.