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The temperature $\theta$ at the junction of two insulating sheets, having thermal resistances $R _{1}$ and $R _{2}$ as well as top and bottom temperatures $\theta_{1}$ and $\theta_{2}$ (as shown in figure) is given by
  • A$\frac{\theta_{1} R_{1}+\theta_{2} R_{2}}{R_{1}+R_{2}}$
  • B$\frac{\theta_{1} R _{2}-\theta_{2} R _{1}}{ R _{2}- R _{1}}$
  • C$\frac{\theta_{1} R _{2}+\theta_{2} R _{1}}{ R _{1}+ R _{2}}$
  • D$\frac{\theta_{1} R_{1}+\theta_{2} R_{2}}{R_{1}+R_{2}}$
JEE MAIN 2021, Medium
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