Question

The plane wall of an oven is of thickness $L=0.05$ m and is exposed to the surrounding at $300$K The outer surface of sathe oven exposed to the surrounding is at temperature $320$ K in steady state. The energy radiated (in $W/m^2)$ by outer surface is proportional to the temperature difference between the surface and the surrounding with proportionally constant $20$ $W/m^2$ K Find the difference in the temperature of inner surface and outer surface of the oven in steady state the wall has a thermal conductivity of $K=5$ W/m K

• A. 4
• B. 8
• C. 12
• D. 20

Answer 1

The correct option is A 4

Let the temperature of inner wall be $T_i$ and that of outer wall be $T_o$. Then, at steady state, net heat current flow through wall be 0.

Hence, $\frac{5A}{0.05}(T_i-T_o)=20A(320-300)$

Ans, $T_i-T_0=4^{o}C$