JEE Main & Advanced Physics Transmission of Heat Question Bank Conduction

  • question_answer
    If the radius and length of a copper rod are both doubled, the rate of flow of heat along the rod increases

    A)            4 times                                   

    B)            2 times

    C)            8 times                                   

    D)            16 times

    Correct Answer: B

    Solution :

                       \[Q\propto \frac{A}{l}\propto \frac{{{r}^{2}}}{l}\] Þ \[\frac{{{Q}_{2}}}{{{Q}_{1}}}=\frac{r_{2}^{2}}{r_{1}^{2}}\times \frac{{{l}_{1}}}{{{l}_{2}}}\]            Þ \[\frac{{{Q}_{2}}}{{{Q}_{1}}}=\frac{4}{1}\times \frac{1}{2}\] Þ \[{{Q}_{2}}=2{{Q}_{1}}\]


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