Question

Two identical conducting rods are first connected simultaneously to two vassels one containing water at 100°C and the other containing ice at 0°C. In second case the two rods are joined end to end and connected to the same two vessels. Let q₁ and q₂ rate of melting of ice in the two cases respectively. The ratio q₁/q₂ is 

(1) 1/2

(2) 2/1

(3) 4/1

(4) 1/4

Answer 1

(3) 4/1

Case I

Fig.(a) shows the two rods A and B. Let a and l denote area of cross-section and of length of each rod. K is thermal conductivity of material of rods.

where L is latent heat of fusion of ice

Case II

The arrangment of rods is an shown in Fig (b)