RADIATION

Heat can be transmitted via conduction, convection and radiation. In conduction, heat travels from the hot end of the body to its cold part. Here motion of heated particles is evaded. If heated particle movement is there, then it is called convection. In radiation, heat transmission takes place without heating the intervening medium. A blackbody absorbs the entire heat radiations incident on it. Blackbody on heating emits radiations which is fully dependent on its temperature. On room temperature, blackbody appear to be black and hence the name. Stefan and Boltzmann put forward a theory for blackbody radiation and according to that the energy radiated per unit area from a blackbody is directly proportional to the fourth power of surface temperature.