CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2010

  • question_answer
    Two charged spherical conductors of radii\[{{R}_{1}}\] and\[{{R}_{2}}\]are connected by a wire. Then the ratio of surface charge densities of the spheres\[{{\sigma }_{1}}/{{\sigma }_{2}}\]is

    A)  \[{{R}_{1}}/{{R}_{2}}\] 

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

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

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

    E)  \[R_{2}^{2}/R_{1}^{2}\]

    Correct Answer: B

    Solution :

    \[\frac{{{q}_{1}}}{{{q}_{2}}}=\frac{{{C}_{1}}}{{{C}_{2}}}=\frac{{{R}_{1}}}{{{R}_{2}}}\] and        \[\frac{{{q}_{1}}}{{{q}_{2}}}=\frac{4\pi R_{1}^{2}{{\sigma }_{1}}}{4\pi R_{2}^{2}{{\sigma }_{2}}}\]                 \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{4\pi R_{1}^{2}{{\sigma }_{1}}}{4\pi R_{2}^{2}{{\sigma }_{2}}}\] \[\therefore \]  \[\frac{{{\sigma }_{1}}}{{{\sigma }_{2}}}=\frac{{{R}_{2}}}{{{R}_{1}}}\]


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