AMU Medical AMU Solved Paper-1998

  • question_answer
    Each of the two conducting spheres of radius 5 cm and 10 cm is given a charge of\[15\mu C\]. After charging the spheres are connected by conducting wire. The charge on the smaller spheres after the connection is equal to.

    A)  \[7.5\mu C\]           

    B)  \[15\mu C\]

    C)  \[10\mu C\]            

    D)  \[20\mu C\]

    Correct Answer: C

    Solution :

    : Common potential of two spheres \[=\frac{{{Q}_{1}}+{{Q}_{2}}}{{{C}_{1}}+{{C}_{2}}}\] \[\therefore \]\[V=\frac{(15+15)\times {{10}^{-6}}}{4\pi {{\varepsilon }_{0}}(5+10)\times {{10}^{-2}}}\] or\[V=\frac{30\times {{10}^{-4}}}{4\pi {{\varepsilon }_{0}}\times 15}=\frac{2\times {{10}^{-4}}}{4\pi {{\varepsilon }_{0}}}\] \[\therefore \]Change on smaller sphere = capacity\[\times V\] \[q=(4\pi {{\varepsilon }_{0}}\times 5\times {{10}^{-2}})\times \frac{2\times {{10}^{-4}}}{4\pi {{\varepsilon }_{0}}}C\] \[=10\times {{10}^{-6}}C=10\,\mu C\]


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