MGIMS WARDHA MGIMS WARDHA Solved Paper-2005

  • question_answer
    Two spheres of radii \[{{R}^{2}}\] and \[{{R}_{1}}\]respectively are charged and joined by a wire. The ratio of electric field of spheres is:

    A) \[R_{2}^{2}/R_{1}^{2}\]                               

    B) \[R_{1}^{2}/R_{2}^{2}\]

    C) \[{{R}_{2}}/{{R}_{1}}\]                                  

    D) \[{{R}_{1}}/{{R}_{2}}\]

    Correct Answer: C

    Solution :

    The sphere are joined by the wire, so their potential will be come equal. \[{{V}_{1}}={{V}_{2}}\] \[\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{q}_{1}}}{{{R}_{1}}}=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{q}_{2}}}{{{R}_{2}}}\] \[\therefore \]  \[\frac{{{q}_{1}}}{{{q}_{2}}}=\frac{{{R}_{1}}}{{{R}_{2}}}\] \[\therefore \]Ratio of Electric fields \[\frac{{{E}_{1}}}{{{E}_{2}}}=\frac{k\frac{{{q}_{1}}}{R_{1}^{2}}}{k\frac{{{q}_{2}}}{R_{2}^{2}}}\]where\[k=\frac{1}{4\pi {{\varepsilon }_{0}}}\] \[=\frac{{{q}_{1}}}{{{q}_{2}}}.{{\left( \frac{{{R}_{2}}}{{{R}_{1}}} \right)}^{2}}\]                 \[=\frac{{{R}_{1}}}{{{R}_{2}}}.{{\left( \frac{{{R}_{1}}}{{{R}_{1}}} \right)}^{2}}\]                 \[=\frac{{{R}_{2}}}{{{R}_{1}}}\]


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