Question

Thermal conductivity of the conductor shown in the figure is $0.92{\text{cal/cm s}}^{\circ }\text{C}$. Find the thermal resistance between points $P$ and $Q$ (in ${\text{s}}^{\circ }\text{C/cal}$).

• A. $0.036$
• B. $0.018$
• C. $0.072$
• D. $1$

Answer 1

The correct option is A $0.036$

Given,
Thermal conductivity $\left(K\right)=0.92{\text{cal/cm s}}^{\circ }\text{C}$
Then, from the definition,
Thermal resistance $\left(R\right)=\frac{l}{KA}$
From $P$ to $Q$, area of cross-section perpendicular to $PQ$ is uniform i.e $(A=lb)$ and length along $PQ$ is $h=2\text{cm}$.
$\therefore R=\frac{2}{0.92\times 60}=0.036{\text{s}}^{\circ }\text{C/cal}$