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
AIPMT 2003, Medium
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(c) $K = \frac{{2{K_1}{K_2}}}{{{K_1} + {K_2}}} = \frac{{2.K.2K}}{{K + 2K}} = \frac{4}{3}K$
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