Answer: alternating.
- A alternating
- B direct
- C perfectly steady
- D zero
Correct answer: A. alternating
Explanation: A transformer needs a changing flux, so it works only on alternating current.
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.