The figure shows a system of two concentric spheres of radii `r_1 and r_2` are kept
Channel: Doubtnut
Date: 2020-07-12

The figure shows a system of two concentric spheres of radii `r_1 and r_2` are kept at temperature `T_1 and T_2`, respectively. The radial rate of flow of heat in a substance between the two concentric spheres is proportional to