Copper wire of diameter d = 5 mm is to be coated with plastic insulation of thermal conductivity k =

Copper wire of diameter d = 5 mm is to be coated with plastic insulation of thermal conductivity k = 0.35 W/m*K for use in an environment with heat transfer coefficient h = 15 W/m^2*K. To minimize the temperature rise of the wire due to ohmic heating, the insulation thickness is specified such that the critical insulation radius is achieved. During the wire coating process, however, the insulation thickness sometimes varies around the periphery of the wire, resulting in eccentricity of the wire relative to the coating. Assuming the exterior surface of the coating to be at uniform temperature, estimate the change in the thermal resistance of the insulation due to an eccentricity (center to center distance) that is 50% of the critical insulation thickness.