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?

Step-by-step solution

Heat conduction through a rod is given by H= Q t =K A ( T₁-T₂ l ) H r^2 l ...(i) (a) When r=2 r₀ ; l=2 l₀ aligned & H (2 r₀ )^2 2 l₀ & H 2 r₀ ^2 l₀ aligned (b) When r=2 r₀ ; l=l₀ aligned & H (2 r₀ )^2 l₀ & H 4 r₀^2 l₀ aligned (c) When r=r₀ ; l=l₀H r₀^2 l₀ (d) When r=r₀ ; l=2 l₀H r₀^2 2 l₀ It is obvious that heat conduction will be more in case (b).