The figure shows a system of two concentric spheres of radii `r_(1)`, and `r_(2)` and kept at temperatures `T_(1)` and `T_(2)`, respectively. The radial rate of flow of heat in a substance between the two concentric spheres is proportional to

Options

A. `((r_(2) - r_(1))/((r_(1)r_(2))`
B. `ln((r_(2))/(r_(1)))`
C. `(r_(1)r_(2))/((r_(2) - r_(1)))`
D. `(r_(2) - r_(1))`

Answer

C

Explanation

Rate of flow of heat =`KA(DeltaT)/(Deltax) = K (4pir_(1)r_(2))((T_(1)-T_(2))/(r_(2) - r_(1)))`