KVPY Sample Paper KVPY Stream-SX Model Paper-5

  • question_answer
    The plates of small size of a parallel plate capacitor are charged as shown. The force on the charged particle of 'q' at a distance \[\ell \] from the capacitor is : (Assume that the distance between the plates is \[d<<\ell )\]

    A) Zero                 

    B) \[\frac{Qqd}{2\pi {{\in }_{0}}{{\ell }^{3}}}\]

    C) \[\frac{Qqd}{\pi {{\in }_{0}}{{\ell }^{3}}}\]                

    D) \[\frac{Qqd}{4\pi {{\in }_{0}}{{\ell }^{3}}}\]

    Correct Answer: A

    Solution :

    [B] The two plates acts as a dipole \[\therefore \]Force on charge q; \[F=Eq=\left( \frac{2kQd}{{{\ell }^{3}}} \right).q=\frac{Qqd}{2\pi {{\varepsilon }_{0}}{{\ell }^{3}}}.\]

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