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Electromagnetic Induction

Question
CBSEENPH12039697

A coil of inductance 300 mH and resistance 2Ω is connected to a source of voltage 2V. The current reaches half of its steady state value in

  • 0.05 s

  • 0.1 s

  • 0.15 s

  • 0.3 s

Solution

B.

0.1 s

straight I space equals space straight I subscript straight o space open parentheses 1 minus straight e to the power of negative straight R over straight L straight t end exponent close parentheses
0.693 space equals straight R over straight L straight t
straight t space equals space fraction numerator 0.3 space straight x space.693 over denominator 2 end fraction space equals space 0.1 space sec

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