As shown in Fig., AB is a rod of length 30 cm and area of cross section 1.0 cm2 and thermal conductivity 336 SI units. The ends A and B are maintained at tempera­tures 20°C and 40°C, respectively. A point C of this rod is connected to a box D, containing ice at 0°C, through a highly conducting wire of negligible heat capacity. The rate at which ice melts in the box is (assume latent heat of fusion for ice Lf = 80 cal/g)