Black body radiation

A body at higher temperatures emits electromagnetic radiation. The rate at which energy is emitted depends on surface temperature and surface conditions. The thermal radiation from a body is composed of wavelengths forming an energy distribution. The total emissive power of a black body  at a particular temperature is

(1)

In which  is wavelength and  is monochromatic emissive power. Planck’s distribution law relates  to the wavelength and temperature:

(2)

In which  is Planck’s constant, a is velocity of light,  is wavelength.  is absolute temperature and  is Boltzmann constant.

Total emissive power of a black body is

(3)

In which  is Stefan’s Boltzmann constant and its value is .