Q. A slab consists of two parallel layers of two different materials of same thickness having thermal conductivities $K_{1}$ and $K_{2}$. The equivalent conductivity of the combination is
A) $K_{1} + K_{2}$
B) $\frac{K_{1} + K_{2}}{2}$
C) $\frac{2K_{1}K_{2}}{K_{1} + K_{2}}$
D) $\frac{K_{1} + K_{2}}{2K_{1}K_{2}}$
Explanation
(b) In parallel combination equivalent conductivity
$K = \frac{K_{1}A_{1} + K_{2}A_{2}}{A_{1} + A_{2}} = \frac{K_{1} + K_{2}}{2}\lbrack As\ A_{1} = A_{2}\rbrack$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.