10B.4. Heat conduction in an annulus (Fig. 10B.4). (a) Heat is flowing through an annular wall of inside radius ro, and outside radius r₁. The thermal conductivity varies linearly with temperature from ko at To to k₁ at T₁. Develop an ex- pression for the heat flow through the wall. (b) Show how the expression in (a) can be simplified when (r₁-ro)/ro is very small. Interpret the result physically. -T)(ko + k) (in 2)" ; (b) Q = 2πral (k + k) (To-T₁) Answer: (a) Q=2πL(T₁ - T₁) In 2