Question

A wall of thickness $0.6\text{m}$ has a normal area $1.5{\text{m}}^2$ and is made up of a material of thermal conductivity $0.4\text{W/mK}$. The temperature difference between the two sides is ${800}^{\circ }\text{C}.$. Find the thermal resistance of the wall.

• A. $1\text{W/K}$
• B. $1.8\text{W/K}$
• C. $1\text{K/W}$
• D. $1.8\text{K/W}$

Answer 1

The correct option is C $1\text{K/W}$


Thermal resistance $R=\frac{\Delta x}{KA}$
Here, $\Delta x=\text{Thickness of the wall}=0.6\text{m}$
$A=\text{Normal area of wall}=1.5{\text{m}}^2$
& $K=\text{thermal conductivity}=0.4\text{W/mK}$
$\Rightarrow R=\frac{0.6}{0.4\times 1.5}=1\text{K/W}$.
Thus, option (c) is the correct answer.