10. The homogeneous spherical wall (inner radius and outer radius ) with thermal conductivity is in a steady state with temperature of the inner surface and of the outer surface , respectively. Assuming that due to conservation of energy, in steady state the same rate of heat transferis passing through a spherical surface of any radius, find the temperature at an arbitrary radius . Derive the differential equation using Fourier’s Law and relation , where is the surface area. Sketch the graph of solution for and , , and determine the rate of heat transfer .