Chapter 2, Problem 2.48P

Passage of an electric current through a long conducting rod of radius $r_i$ and thermal conductivity $k_r$ results in uniform volumetric heating at a rate of $\stackrel{.}{q}.$ The conducting rod is wrapped in an electrically nonconducting cladding material of outer radius $r_o$ and thermal conductivity $k_c,$
and convection cooling is provided by an adjoining fluid.

For steady-state conditions, write appropriate forms of the heat equations for the rod and cladding. Express appropriate boundary conditions for the solution of these equations.