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Haryana PMT Haryana PMT Solved Paper-2010

  • question_answer
    A coil of Cu wire (radius r, self-inductance L) is bent in two concentric turns each having  radius \[\frac{r}{2.}\] The self-inductance is now

    A)  2L                                          

    B)  L

    C)  4L                                          

    D)  \[\frac{L}{2.}\]

    Correct Answer: A

    Solution :

                    As   \[L\propto {{N}^{2}}r\] \[\frac{{{L}_{1}}}{{{L}_{2}}}={{\left[ \frac{{{N}_{1}}}{{{N}_{2}}} \right]}^{2}}\times \frac{{{r}_{1}}}{{{r}_{2}}}\]                 \[\Rightarrow \]               \[\frac{L}{{{L}_{2}}}={{\left[ \frac{1}{2} \right]}^{2}}\times \left[ \frac{r}{r/2} \right]=\frac{1}{2}\]                                 \[{{L}_{12}}=2L\]


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