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

  • question_answer
    A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency If an ac source, of 200 volt, 100 Hz, is connected across the coil, the current in the coil will be

    A) 4.0 A

    B) 8.0 A

    C) \[\frac{20}{\sqrt{13}}\,A\]

    D) 2.0 A

    Correct Answer: A

    Solution :

    [a] If \[\omega =50\times 2\pi \] then \[\omega L=20\Omega \] If \[\omega '=100\times 2\pi \] then  \[\omega 'L=40\Omega \] Current flowing in the coil is \[I=\frac{200}{Z}=\frac{200}{\sqrt{{{R}^{2}}+{{(\omega 'L)}^{2}}}}=\frac{200}{\sqrt{{{(30)}^{2}}+{{(40)}^{2}}}}\]


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