Answer: 2 V.
- A 0.5 V
- B 2 V
- C 4 V
- D 8 V
Correct answer: B. 2 V
Explanation: emf = M dI/dt = 0.5·4 = 2 V.
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.