Which of the following circular rods, (given radius r and length l) each made of the same energy material and whose ends are maintained at the same temperature will conduct most heat :

r = 2r0; l = 2l0 r = 2r0 ; l = l0 r = r0 ; l = 2l0 r = r0 ; l =l0

r = 2r0 ; l = l0

Rheat = \(\frac{l}{KA} = \frac{l}{K \pi r^2}\)