41 - Radiation

Planck’s Distribution Law gives the relation for spectral emissive power \(E_{b\lambda}(T)\) of a black body as a function of temperature and wavelength. \[\boxed{E_{b\lambda}(T) = \frac{c_1}{\lambda^5\{\exp[c_2/(\lambda T)]-1\}} \qquad \text{W/(m$^2$.$\mu$m)} }\] where

According to this law, at any given wavelength, the emissive power increases with increase in temperature; and, at any given temperature, the emitted radiation varies with wavelength and shows a peak. These peaks tend to shift toward smaller wavelengths as the temperature increases. The locus of these peaks is given by Wien’s displacement law.