Question

In the following figure, two insulating sheets with thermal resistances R and 3R as shown in figure. The temperature $\theta$ is

• A. ${200}^{\circ }$ C
• B. ${60}^{\circ }$ C
• C. ${75}^{\circ }$ C
• D. ${80}^{\circ }$ C

Answer 1

The correct option is D ${80}^{\circ }$ C

For the two sheets $H_1=H_2$ (H = Rate of heat flow)
$\Rightarrow \frac{(100-\theta )}{R}=\frac{(\theta -20)}{3R}\Rightarrow \theta ={80}^{\circ }C$