A 0.082-in-diameter electrical wire at 90∘F is covered by 0.02-inthick plastic insulation (k=0.075 Btu/h⋅ft⋅F). The wire is exposed to a medium at 50 F, with a combined convection and radiation heat transfer coefficient of 2.5 Btu/h⋅ft². F. Assume a thermal contact resistance of 0.001 h⋅ft²⋅F/Btu at the interface of the wire and the insulation.

a. Calculate the total thermal resistance of the electrical wire with insulation.