Consider two insulating sheets with thermal resistances $R_1$ and $R_2$ as shown. The temperatures $\theta $ is

823-1549

  • A

    $\frac{{{\theta _1}{\theta _2}{R_1}{R_2}}}{{({R_1} + {R_2})({\theta _1} + {\theta _2})}}$

  • B

    $\frac{{{\theta _1}{R_1} + {\theta _2}{R_2}}}{{{R_1} + {R_2}}}$

  • C

    $\frac{{({\theta _1} + {\theta _2})\left( {{R_1}{R_2}} \right)}}{{R_1^2 + R_2^2}}$

  • D

    $\frac{{{\theta _1}{R_2} + {\theta _2}{R_1}}}{{{R_1} + {R_2}}}$

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