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GATE 2021 BM – Question 14

Electrical Circuits · AC Circuits and Resonance · 1 mark · Multiple choice

An ideal 1/3 H inductor is connected to a 50 Hz sinusoidal voltage source. The energy stored is stated as 6 J. Find the maximum power delivered to the inductor in W.

  1. 1200π
  2. 600π
  3. 1200
  4. 0

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Show answer and explanation

Correct answer: (A) 1200π

Explanation

The official A treats the stated six joules as cycle-average magnetic energy. With sinusoidal current, average energy is LIrms²/2 and instantaneous power amplitude is ωLIrms²=2ωEavg. Thus Pmax=2×(2π×50)×6=1200π W. If six joules meant maximum stored energy instead, Pmax would be 600π W, B. The source does not specify average versus peak energy; the official grading is retained with its necessary interpretation. Average real power in an ideal inductor remains zero.

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