Asking for hand written detail solution:

Consider a spherical chamber immersed in the ocean at great depth. The walls are thick and made of a hard plastic material with thermal conductivity g. Inside the chamber an electric circuit generates heat at the rate H. Thus H is thermal energy generated per second. The inner radius of the spherical shell is a and the outer radius is b. Suppose the ocean temperature outside the sphere is T_low and suppose that in a steady state, the circuit keeps the inner temperature constant at T_high . Calculate T_high in terms of g, H, a, b and T_low .