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MHT CET 2021 (23 Sep, Shift 2) · Combination of Inductors, LR & LC Circuits

Combination of Inductors, LR & LC Circuits question from MHT CET 2021 (23 Sep, Shift 2)

Q28MHT CET 2021 · 23 SEP · SHIFT 2Medium

Combination of Inductors, LR & LC Circuits

A circuit has self-inductance 'L' H and carries a current 'I' A. To prevent sparking when the circuit is switched off, a capacitor which can withstand 'V' volt is used. The least capacitance of the capacitor connected across the switch must be equal to

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Answer: (c)

  1. On switching off, the magnetic energy of the inductor must be taken up by the capacitor.
  2. 12LI2=12CV2\frac{1}{2}LI^2 = \frac{1}{2}CV^2
  3. C=LI2V2=L(IV)2C = \frac{LI^2}{V^2} = L\left(\frac{I}{V}\right)^2
  4. So the answer is (c).
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