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 lengths $l_1$ and $l_2$ and thermal conductivities $K_1$ and $K_2$ respectively. The temperature at the interface of the two sections is

815-279

  • A

    $\left( {{K_2}{l_2}{T_1} + {K_1}{l_1}{T_2}} \right)/\left( {{K_1}{l_1} + {K_2}{l_2}} \right)$

  • B

    $\left( {{K_2}{l_1}{T_1} + {K_1}{l_2}{T_2}} \right)/\left( {{K_2}{l_1} + {K_1}{l_2}} \right)$

  • C

    $\left( {{K_1}{l_2}{T_1} + {K_2}{l_1}{T_2}} \right)/\left( {{K_1}{l_2} + {K_2}{l_1}} \right)$

  • D

    $\left( {{K_1}{l_1}{T_1} + {K_2}{l_2}{T_2}} \right)/\left( {{K_1}{l_1} + {K_2}{l_2}} \right)$

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