# Explain why a room heated by a radiator warms up throughout, even in parts of the room far from the radiator, by describing the process of convection.

> Cambridge International IGCSE Physics (0625) — 2.3 Transfer of thermal energy · Explain · 4 marks

> A central-heating radiator is fixed to the wall of a room. After the radiator is switched on, the air throughout the entire room gradually warms up.

## Mark scheme (4 marks)

1. The air in contact with the radiator is heated and expands
2. The heated air becomes less dense and rises
3. Cooler, denser air sinks and moves towards the radiator to replace the rising warm air
4. This sets up a convection current that circulates thermal energy throughout the room

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Physics (0625)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-a-room-heated-by-d4d198c1) · Published by Druglandscape Ltd.