Q. The thermal conductivity of a material in CGS system is 0.4. In steady state, the rate of flow of heat is $10\ cal/s$-$cm^{2}$, then the thermal gradient will be
A) $10℃/cm$
B) $12℃/cm$
C) $25℃/cm$
D) $20℃/cm$
Explanation
(c) $\frac{\mathrm{\Delta}Q}{\mathrm{\Delta}t} = \frac{KA\mathrm{\Delta}\theta}{\mathrm{\Delta}x} \Rightarrow$ Thermal gradient $\frac{\mathrm{\Delta}\theta}{\mathrm{\Delta}x}$
$= \frac{(\mathrm{\Delta}Q/\mathrm{\Delta}t)}{KA} = \frac{10}{0.4} = 25℃/cm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.