Q. Which of the following circular rods. (given radius $r$ and length $l$) each made of the same material as whose ends are maintained at the same temperature will conduct most heat?
A) $r = 2r_{0};l = 2l_{0}$
B) $r = 2r_{0};l = l_{0}$
C) $r = r_{0};l = l_{0}$
D) $r = r_{0};l = 2l_{0}$
Explanation
(b) Heat current $\frac{\mathcal{Q}}{t} \propto \frac{r^{2}}{l}$, from the given options, option (b) has higher value of $\frac{r^{2}}{l}$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.