JIPMER Jipmer Medical Solved Paper-2010

  • question_answer
    Figure shows three spherical and equipotential surfaces A, B and C round a point charge q. The potential difference \[{{V}_{A}}-{{V}_{B}}={{V}_{B}}-{{V}_{C.}}\] If \[{{t}_{1}}\] and \[{{t}_{2}}\] be the distances between them, then

    A)  \[{{t}_{1}}={{t}_{2}}\]          

    B)                         \[{{t}_{1}}>{{t}_{2}}\]                   

    C)         \[{{\text{t}}_{\text{1}}}<{{\text{t}}_{\text{2}}}\]                            

    D)         \[{{t}_{1}}\le {{t}_{2}}\]

    Correct Answer: C

    Solution :

    Potential difference between two equipotential surfaces A and B, \[{{V}_{A}}-{{V}_{B}}=kq\left( \frac{1}{{{r}_{A}}}-\frac{1}{{{r}_{B}}} \right)=kq\left( \frac{{{r}_{B}}-{{r}_{A}}}{{{r}_{A}}{{r}_{B}}} \right)=\frac{kq{{t}_{1}}}{{{r}_{A}}{{r}_{B}}}\] or            \[{{t}_{1}}=\frac{({{V}_{A}}-{{V}_{B}})\,{{r}_{A}}{{r}_{B}}}{kq}\] or            \[{{t}_{1}}\propto {{r}_{A}}{{r}_{B}}\] Similarly, \[{{t}_{2}}\propto {{r}_{B}}{{r}_{C}}\] Since, \[{{r}_{A}}<{{r}_{B}}<{{r}_{C}},\] therefore, \[{{r}_{A}}{{r}_{B}}<{{r}_{B}}{{r}_{C}}\] \[\therefore \]  \[{{t}_{1}}<{{t}_{2}}\]


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