Discussion
Two identical metal containers are taken. Container A is painted black and the container B is painted white on the outside surface.
Step 1 : Both the containers are kept in direct sunlight.
Step 2 : After few hours, both the containers are kept in a shady area.
Which of the following will be observed?
Answer: C
Container A will gain as well as lose heat faster than container B.
A black surface is a good absorber of heat radiation and an equally good emitter. In sunlight the black container A absorbs radiation faster and heats up faster; in the shade it radiates heat faster and cools down faster.
A white surface reflects most radiation, so container B both gains and loses heat more slowly. The options that split the roles, or make B faster in either step, contradict the rule that good absorbers are good emitters.
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