Heat Transfer

A point source of heat of power $P$ is placed at the center of a spherical shell of mean radius $R$ . The material of the shell has thermal conductivity $K$ . Calculate the thickness of the shell if the temperature difference between the outer and inner shell in steady state is $T$ .

The thickness $t$ can be given by: $\frac{A R^2 K T}{P}$ , where $A$ is a constant.

Find the value of $A$ correct upto three decimal places.