JEE Main & Advanced Physics Alternating Current / प्रत्यावर्ती धारा Question Bank Self Evaluation Test - Alternating Current

  • question_answer
    A coil of inductance 8.4 mH and resistance \[6\,\Omega \] is connected to a 12 V battery. The current in the coil is 1.0 A at approximately the time

    A) 500s

    B) 25s 

    C) 35ms

    D) 1ms

    Correct Answer: D

    Solution :

    [d] Using \[I={{I}_{0}}(1-{{e}^{-t/\tau }})\] But \[{{I}_{0}}=\frac{V}{R}\]  and  \[\tau =\frac{L}{R}\] \[\therefore \,\,\,\,I=\frac{V}{R}(1-{{e}^{-Rt/L}})=\frac{12}{6}\left[ 1-{{e}^{-6t/8.4\times {{10}^{-3}}}} \right]\] =1 (given) \[\therefore \,\,\,t=0.97\times {{10}^{-3}}\,s\approx 1ms\]


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