Answer: 1.28 W.
- A 1.28 W
- B 0.64 W
- C 2.56 W
- D 5.12 W
Correct answer: A. 1.28 W
Explanation: Induced emf = Blv = 1.6 V and current = 1.6/2 = 0.8 A. Mechanical power equals electrical power lost as heat: P = I<sup>2</sup>R = 0.8<sup>2</sup> × 2 = 1.28 W.
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.