Transmission Of Heat Question 78

Question: Consider a compound slab consisting of two different materials having equal thickness and thermal conductivities K and 2K respectively. The equivalent thermal conductivity of the slab is

[CBSE PMT 2003]

Options:

A) $ \sqrt{2K} $

B) $ 3K $

C) $ \frac{4}{3}K $

D) $ \frac{2}{3}K $

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Answer:

Correct Answer: C

Solution:

$ K=\frac{2K _{1}K _{2}}{K _{1}+K _{2}}=\frac{2.K.2K}{K+2K}=\frac{4}{3}K $