Answer: Doubles.
- A Remains unchanged
- B Becomes four times as large
- C Doubles
- D Becomes half as large
Correct answer: C. Doubles
Explanation: Motional EMF is given by ε = Bvl, which is directly proportional to velocity v, so doubling v doubles the EMF.
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.