NEET Sample Paper NEET Sample Test Paper-14

  • question_answer A rigid conducting wire bent as shown, is released to fall freely in a horizontal magnetic field, which is perpendicular to the plane of the conductor. If magnetic field strength is B, then the emf induced across the points A and when it has fallen through a height h will be:

    A)  \[B\ell \sqrt{2gh}\]                 

    B) \[B\ell \sqrt{gh}\]

    C) \[2B\ell \sqrt{gh}\]                  

    D) \[2B\ell \sqrt{2gh}\]

    Correct Answer: C

    Solution :

    The effective length is \[AC={{l}_{0}}=\sqrt{{{\ell }^{2}}+{{\ell }^{2}}}=\sqrt{2}\ell \] Induced emf \[=\varepsilon -B{{l}_{0}}v\] \[=B\sqrt{2}\ell \sqrt{2gh}=2B\ell \sqrt{gh}\] \[[\because \,v=\sqrt{2gh}]\] Hence, the correction option is [c].


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