Stefan-Boltzmann law (Stefan, L. Boltzmann):
The radiated power P (it is rate of emission of electromagnetic energy) of hot body is proportional to the radiating surface area, A, & the fourth power of the thermodynamic temperature, T. The constant of proportionality refer to the Stefan-Boltzmann constant. Mathematically specking,
P = e sigma A T^{4},
Where the efficiency rating e refer to the emissivity of the object.