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JEE Main & Advanced Physics Electro Magnetic Induction Question Bank Self Evaluation Test - Electromagnetic Induction

  • question_answer
    In an inductor of self-inductance L=2mH, current changes with time according to relation \[i={{t}^{2}}{{e}^{-t}}\]. At what time emf is zero?

    A) 4s

    B) 3s   

    C) 2s

    D) Is

    Correct Answer: C

    Solution :

    [c] \[L=2mH\],  \[i={{t}^{2}}{{e}^{-t}}\] \[E=-L\frac{di}{dt}=-L[-{{t}^{2}}{{e}^{-t}}+2t{{e}^{-t}}]\] when \[E=0,\,\,-{{e}^{-t}}{{t}^{2}}+2t{{e}^{-t}}=0\] or, \[2t\,{{e}^{-t}}={{e}^{-t}}\,{{t}^{2}}\Rightarrow t=2\,\sec \].


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