Q. Two identical plates of different metals are joined to form a single plate whose thickness is double the thickness of each plate. If the coefficients of conductivity of each plate are 2 and 3 respectively, then the conductivity of composite plate will be
A) 5
B) 2.4
C) 1.5
D) 1.2
Explanation
(b) Thermal conductivity of composite plate
$K_{eq} = \frac{2K_{1}K_{2}}{K_{1} + K_{2}} = \frac{2 \times 2 \times 3}{2 + 3} = \frac{12}{5} = 2.4$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.