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JEE Main & Advanced Physics EM Waves Question Bank Self Evaluation Test - Electromagnetic Waves

  • question_answer
    A circular ring of radius r is placed in a homogeneous magnetic field perpendicular to the plane of the ring. The field B changes with time according to equation \[B=kt,\]where, k is a constant and t is the time). The electric field in the ring is:               

    A) \[\frac{kr}{4}\]

    B) \[\frac{kr}{3}\]   

    C) \[\frac{kr}{2}\]

    D) \[\frac{k}{2r}\]

    Correct Answer: C

    Solution :

    [c] \[\oint{\vec{E}.d\vec{\ell }=-\frac{d{{\phi }_{B}}}{dt}}\] or \[E(2\pi r)=\frac{d}{dt}(kt\times \pi {{r}^{2}})\]         \[\therefore \,\,\,E=\frac{kr}{2}\]


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