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⚛️ Physics  ·  Electromagnetic Induction  ·  NEET & JEE

A rectangular conducting loop of resistance 4 Ω moves completely out of a uniform magnetic field. If the total change in flux per turn is 0.08 Wb and the loop has 20 turns, the total charge passing through the loop is:

Answer: 0.40 C.

  • A 0.20 C
  • B 0.40 C
  • C 0.80 C
  • D 1.60 C

Correct answer: B. 0.40 C

Explanation: The total charge is q = NΔΦ/R = 20 × 0.08/4 = 0.40 C.

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 →