Q 11-10-043NEETJEE MainEasy
Two rods of the same material and length have radii in the ratio $1 : 2$. With the same temperature difference across their ends, the ratio of their rates of heat flow is
Answer: (B) $1 : 4$
Concept. $\dfrac{Q}{t} = \dfrac{KA\Delta\theta}{l}$; same material, length and $\Delta\theta$, so the rate $\propto A \propto r^2$.
Step 1. Ratio. $\left(\dfrac12\right)^2 = \dfrac14$.
Answer. $1 : 4$ (Option B).
Solution by Sreeraj P, M.Sc Physics