Q. Which of the following circular rods, (given radius r and length l) each made of the same material and whose ends are maintained at the same temperature will conduct most heat ?
A) r = 2r₀; l = 2l₀
B) r = 2r₀; l = l₀
C) r = r₀; l = l₀
D) r = r₀; l = 2l₀
Explanation
[Solution from source] Heat current H = kAΔT/l ∝ r²/l. For r = 2r₀, l = l₀ this is 4r₀²/l₀, the largest; r = 2r₀, l = 2l₀ gives only 2r₀²/l₀. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.