Heat Transfer
3.0 Radiation
3.0 Radiation
Radiation is completely a different process of heat transfer. It does not need any material medium.
The sun radiation is a good example of radiation heat transfer.
Radiation energy is emitted by a source and it travels through the space. When this radiation falls on any surface, a part of it is absorbed by the surface which causes increase in its temperature. The energy emitted by the body in this way is known as radiation energy.
Prevost's theory of exchange tells that all bodies radiate thermal energy at all temperatures.
The amount of radiation radiated per unit time depends on the nature of the material, area and its surroundings.
If a body is radiating energy, it will also absorb the radiation from the surroundings.
If a body radiate more heat than absorbtion, the temperature of the body decreases.
The rate of emission is equals to the rate of absorption.
