NTA Abhyas JEE Main2020PhysicsThermal Properties of MatterPractice
Four rods, of different radii r and length l , are used to connect two reservoirs of heat at different temperatures. The rod that will conduct the heat fastest will be
Options
- Ar = 2 cm , l = 0.5 m
- Br = 1   cm ,   l = 0.5   m
- Cr = 2   cm ,   l = 2   m
- Dr = 1   cm ,   l = 1   m
Correct answer
A. r = 2 cm , l = 0.5 m
Step-by-step solution
∆ T ∆ t = K A ∆ T ∆ x = K π r 2 ∆ T l ∴ ∆ Q ∆ t ∝ r 2 l , which is maximum in this case.