Question

A wall has $2$ layer $A$ and $B$ each made of different material, both the layers have the same thickness. The thermal conductivity of the material $A$ is twice that of $B$. Under steady state the temperature difference across the wall $B$ is ${36}^{\circ }C$. The temperature difference across the wall $A$ is :

• A. $6^{\circ }C$
• B. ${12}^{\circ }C$
• C. ${18}^{\circ }C$
• D. ${72}^{\circ }C$

Answer 1

The correct option is C ${18}^{\circ }C$

In steady state $\frac{Q}{t}=KA\frac{dT}{dx}$

$\Delta T\propto \frac{1}{k}$ as other parameters are constant

$\Delta T=\frac{1}{2}\times 36={18}^{o}C$