Solar power producing heat
2 marks · EasyExplain why the pipes inside a solar heating panel are usually painted black.
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Black surfaces absorb more thermal radiation, so painting the pipes black increases heat transfer to the water.
Also accept: Black surfaces absorb more energy.
Common mistakes: Reflect more heat; Look good
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Marking points
M1 · 1 mark · States that black objects absorb more thermal radiation (or heat).
A1 · 1 mark · Links increased absorption to more efficient heating of water.
Worked solution
Black surfaces are good absorbers of thermal radiation. Therefore, painting the pipes black increases the absorption of the Sun's energy, making the heating of the water more efficient.