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A body has same temperature as that of the surroundings. The ratio of radiations emitted and radiations received from the surroundings is

A body has same temperature as that of the surroundings. The ratio of radiations emitted and radiations received from the surroundings is Correct Answer One

Concept-

  • According to the theory of exchange, all bodies radiate thermal radiation at all temperatures. The amount of thermal radiation radiated per unit time depends on the nature of the emitting surface, its area and its temperature. The rate is faster at higher temperature.
  • Apart from that, a body also absorbs part of the thermal radiation emitted by the surrounding bodies when this radiation falls on them.
  • If a body radiates more than what it absorbs, it temperature falls. Similarly, if a body radiates less than what it absorbs, it temperature rises.

 

Explanation-

  • Suppose a body is kept in a room for a long time. We find that the temperature of the body remains constant and is equal to the room temperature. The body is still radiating thermal radiation. But at the same of point, it is also absorbing part of radiation emitted by the surrounding objects.
  • We thus conclude that when the temperature of a body is equal to the temperature of its surroundings, it radiates at the same rate as it absorbs. So the ratio will be 1.

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