Question

A plane wall is $25\text{cm}$ thick with an area of $1{\text{m}}^2$ and has a thermal conductivity of $0.5\text{W/mK}$. If a temperature difference of ${60}^{\circ }\text{C}$ is maintained across it, then find the rate of heat flow.

• A. $120\text{W}$
• B. $140\text{W}$
• C. $160\text{W}$
• D. $180\text{W}$

Answer 1

The correct option is A $120\text{W}$

We know that, rate of heat flow
$\frac{\Delta Q}{\Delta T}=kA\frac{T_2-T_1}{l}$
From the data given in the question,
$\frac{\Delta Q}{\Delta T}=0.5\times 1\times \frac{60}{0.25}$
$\Rightarrow \frac{\Delta Q}{\Delta T}=120\text{W}$
Hence, option (a) is the correct answer.