A parallel-sided slab is made of two different materials. The upper half of the slab is made of material X of thermal conductivity λ . The lower half is made of material Y of thermal conductivity 2 λ

Question

A parallel-sided slab is made of two different materials. The upper half of the slab is made of material $X$ of thermal conductivity $λ$ . The lower half is made of material $Y$ of thermal conductivity $2 λ$ . In the steady state, the left-hand face of the composite slab is at a higher uniform temperature than the right-hand face, and the flow of heat through the slab is parallel to its shortest sides. What fraction of the total heat flow through the slab passes through material $X$ ?

Options:

Answer:

B

Solution:

The two halves are in parallel with equal areas and the same temperature difference. The flows are in the ratio $λ : 2 λ$ , so $X$ carries $\frac{1}{3}$ . B.

TestHub · Accepted Answer

The two halves are in parallel with equal areas and the same temperature difference. The flows are in the ratio λ : 2 λ , so X carries 3 1 ​ . B.

Physics - Heat & Thermo Question with Solution | TestHub

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