A hollow sphere with inner and outer radii of R1 and R2, respectively, is covered with a

Question:

A hollow sphere with inner and outer radii of R1 and R2, respectively, is covered with a layer of insulation having an outer radius of R3. Derive an expression for the rate of heat transfer through the insulated sphere in terms of the radii, the thermal conductivities, the heat transfer coefficients, and the temperatures of the interior and the surrounding medium of the sphere.GIVENAn insulated hollow sphereRadiiInner surface of the sphere = R1Outer surface of the sphere = R2Outer surface of the insulation = R3ASSUMPTIONSSteady state heat transferConduction in the radial direction onlyConstant thermalconductivities