# Explain why a black, dull-surfaced metal container of hot water cools down more quickly than an identical shiny, white-surfaced container of hot water at the same initial temperature, when both are placed in the same surroundings.

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

## Mark scheme (4 marks)

1. Black/dull surfaces are good emitters of thermal (infrared) radiation
2. White/shiny surfaces are poor emitters of thermal (infrared) radiation
3. The black container therefore loses thermal energy at a greater rate by radiation
4. Since the black container loses energy faster, its temperature falls more quickly / it cools down faster than the shiny container

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