Two solid rods are made of the same material with the same thermal conductivity. They are insulated on their outer radius and have the same temperatures on either end, as shown. The diameter of rod A is twice that of rod B and the length of rod A is half that of rod B. Determine the ratio of the thermal resistance of rod B to the thermal resistance of rod A (along their centerline).

LA direction of heat flow DA C Rod A TA LB = 2 LA T2 Dp = D./21 Rod B