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⚛️ Physics  ·  Electromagnetic Induction  ·  NEET & JEE

The peak emf of a coil rotating in a magnetic field is NBAω. If the angular speed ω is doubled, the peak emf:

Answer: doubles.

  • A halves
  • B doubles
  • C is unchanged
  • D becomes four times

Correct answer: B. doubles

Explanation: Peak emf ∝ ω, so doubling ω doubles the peak emf.

EMF is Induced Only While Flux is ChangingΦmagnet approachingmagnet stationary inside coilEMFEMF ≠ 0 (flux changing)EMF = 0 (flux constant)t

As a magnet approaches a coil, flux rises steadily and a constant non-zero EMF is induced (Faraday's law). Once the magnet stops moving, flux stays constant and the induced EMF drops to zero - EMF only exists while flux is actively changing.

Concept context

Faraday's and Lenz's laws, motional EMF, self/mutual inductance, eddy currents, and the AC generator - how a changing magnetic flux creates an electric current.

Read the full Electromagnetic Induction notes →