Application and consequences of radiation:

A black and rough surface absorbs more heat than a white or polished surface. Since good absorbers are also good radiators of heat. Thus, a black-colored body gets hot quickly absorbing heat reaching it during a sunny day, and also cools down quickly by giving out its heat to its surroundings.

The bottoms of cooking pots are made black to increase the absorption of heat from the fire. White surfaces reflect more than colored or black surfaces. Similarly, polished surfaces are good reflectors than rough surfaces, and the reflection of heat radiations is greater from polished surfaces. Hence, we wear white or light-colored clothes in summer which reflect most of the heat radiation reaching us on a hot day.

We polish the interior of the cooking and hot pots for reflecting most of the heat radiation within them.

FOR YOUR INFORMATION

In a thermos flask, most of the heat is prevented to enter or leave the flask. This is done by suitable measures to reduce the transfer of heat due to conduction, convection, and radiation. Thus, anything kept in it maintains its temperature for a long time.