Question
two identical conducting rods are first connected independently to two vessels, one containing water at 100°C and the other containing ice at 0°C. In the second case, the rods are joined end to end connected to the same vessels. Let M1 and M2 g/s be the rate of melting of ice in the two cases respectively, the ratio M1/M2 is
(1) 1:2
(2) 2:1
(3) 4:1
(4) 1:4
Joshi sir comment
in first case rods are taken in parellel so net length and area will be l and 2A with conductivity coefficient K
similarly in second case rods are taken in series so net length and area will be 2l and A with conductivity coefficient K
now use H = KA(θ1- θ2)/L and H = dQ/dt = mL/t L is latent heat which is fixed in both the cases