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KVPY Sample Paper KVPY Stream-SX Model Paper-7

  • question_answer
    For a charged circular ring, maximum value of electrical potential is at

    A) A                                 

    B)  B    

    C) C                                 

    D) D

    Correct Answer: B

    Solution :

    \[{{E}_{axis}}=\frac{kxQ}{{{\left( {{x}^{2}}+{{R}^{2}} \right)}^{3/2}}}\]
    \[{{E}_{\max }}\Rightarrow when\frac{dE}{dx}=0\Rightarrow x=\pm \frac{R}{\sqrt{2}}\]
    From \[\frac{dV}{dr}=-E\],- we have
    \[{{V}_{\max }}=\frac{Q}{2\sqrt{6}\pi {{\in }_{0}}}\]
    Which occurs at B.


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