A copper slab 1 text m thick connects a heat source at 10^3 text K to a reservoir at 10^2 text K . If the thermal conductivity of copper is 0.1 text WK ^ -1 text m ^ -1 , what is the energy flux through the slab in steady state?

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EEJ MAIN Physics QUESTION #7054

Question 1

A copper slab $1 \text{ m}$ thick connects a heat source at $10^3 \text{ K}$ to a reservoir at $10^2 \text{ K}$. If the thermal conductivity of copper is $0.1 \text{ WK}^{-1}\text{m}^{-1}$, what is the energy flux through the slab in steady state?

$90 \text{ Wm}^{-2}$✔️
$120 \text{ Wm}^{-2}$
$65 \text{ Wm}^{-2}$
$200 \text{ Wm}^{-2}$

Correct Answer Explanation

Energy flux (Intensity) is the rate of heat flow per unit area:

$J = \frac{H}{A} = \frac{k \Delta T}{L}$

$J = \frac{0.1 \times (10^3 - 10^2)}{1} = 0.1 \times 900 = 90 \text{ Wm}^{-2}$

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