158.

For small values of $\lambda T$ (i.e., small compared with the constant ${\displaystyle \frac{ch}{k}}$) equation [eqn:(276)] (276) becomes $E_{\lambda }=\frac{c^{2}h}{{\lambda }^5}{e}^{-\frac{ch}{k\lambda T}}\mathrm{\backslash Label}[eqn](280)\text{upshape (280)}$ an equation which expresses Wien'sW. Wien, Wied. Ann. 58, p. 662, 1896. law of energy distribution.

The specific intensity of radiation $𝖪$ then becomes, according to [eqn:(274)] (274), $𝖪=\frac{h{\nu }^3}{c^2}{e}^{-\frac{h\nu }{kT}}\mathrm{\backslash Label}[eqn](281)\text{upshape (281)}$ and the space density of energy $𝗎$ is, from [eqn:(275)] (275), $𝗎=\frac{8\pi h{\nu }^3}{c^3}{e}^{-\frac{h\nu }{kT}}.\mathrm{\backslash Label}[eqn](282)\text{upshape (282)}$