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MHT CET 2025 (20 Apr, Shift 2) · Motional EMF

Motional EMF question from MHT CET 2025 (20 Apr, Shift 2)

Q15MHT CET 2025 · 20 APR · SHIFT 2Medium

Motional EMF

A simple pendulum with bob of mass m and conducting wire of length LL swings under gravity through an angle θ\theta. The component of earth's magnetic field in the direction perpendicular to swing is B. Maximum e.m.f. induced across the pendulum is ( g=g = acceleration due to gravity)

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Answer: (a)

  1. Maximum speed at the lowest point: v=2gL(1−cos⁡θ)=2gLsin⁡θ2v = \sqrt{2gL(1-\cos\theta)} = 2\sqrt{gL}\sin\frac{\theta}{2}.
  2. Taking εmax=BLvmax\varepsilon_{max} = BLv_{max} (the usual exam approach):
  3. εmax=2BLgLsin⁡θ2\varepsilon_{max} = 2BL\sqrt{gL}\sin\frac{\theta}{2}
  4. So the answer is (a).
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