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NEET Sample Paper NEET Sample Test Paper-69

  • 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 now

    A) 2 L                  

    B)   L

    C) 4 L                              

    D) L/2

    Correct Answer: A

    Solution :

    \[\because \,\,\,\,\,\,\,L\propto {{N}^{2}}r;\,\,\,\frac{{{L}_{1}}}{{{L}_{2}}}={{\left( \frac{{{N}_{1}}}{{{N}_{2}}} \right)}^{2}}\times \frac{{{r}_{1}}}{{{r}_{2}}}\] \[\Rightarrow \,\,\,\,\,\,\,\,\frac{L}{{{L}_{2}}}={{\left( \frac{1}{2} \right)}^{2}}\times \left( \frac{r}{r/2} \right)=\frac{1}{2};\,\,\,\,{{L}_{2}}=2L\]


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