Describe an experiment to show the rate of heat loss from a body depends on the nature of the surface.

A cubical metal tank whose sides are painted; dull black, dull white and highly polished is filled with hot water and radiations from each surface are detected by a thermopile as shown below.

The galvanometer deflection is greatest when the thermopile is facing the dull black surface and least when facing a highly polished silver surface. Therefore, a polished surface is the least radiator and a black surface is the best radiator. Hence, rate of heat loss from a body depends on the nature of the surface.

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Dr. Bbosa Science