Stefan Boltzmann law The rate of energy radiated from a blackbody at absolute temperature T, with surface area, is given by Stefan Boltzmann law.
dQ/dt = s aT4 (s16)
where s = 5.67´ 10-8W.m-2.K-4 is the Stefan Boltzmann constant. If the body is not a blackbody, then the expression (s16) is multiplied by emissivity of its surface. If the surrounding temperature is T0, then the amount of heat radiated by the blackbody is given by,
dQ/dt =s A(T4- T04 ) (s17)
The second term is due to the heat absorbed by the body.