Chapter 39, Problem 39.61P

(a)

To determine

The expression for $I\left(f\right)$, the Planck distribution law in terms of frequency $f$.

(b)

To determine

To show: the integral ${\displaystyle {\int }_0^{\infty }I}\left(\lambda \right)=\frac{2{\pi }^5{k}^4}{15c^2{h}^3}{T}^4$.

(c)

To determine

The constants in part (b) and to show that $\sigma$ has the value given in Section $39.5$.