One end of a thermally insulated rod is kept at a temperature `T_1` and the other at `T_2`. The rod is composed of two sections of length `l_1 and l_2` and thermal conductivities `K_1 and K_2` respectively. The temperature at the interface of the two section is

Options

A. `(k_2l_2T_1 +k_1 l_1 T_2)//(k_1 l_1 + k_2l_2)`
B. `(k_2l_1T_1 +k_1 l_2 T_2)//(k_2 l_1 + k_1l_2)`
C. `(k_1l_2T_1 +k_1 l_2 T_2)//(k_1 l_2 + k_2l_1)`
D. `(k_1l_1T_1 +k_2 l_2 T_2)//(k_1 l_1 + k_2l_2)`

Answer

C