Answer: 10 A.
- A 0.4 A
- B 10 A
- C 2.5 A
- D 5 A
Correct answer: B. 10 A
Explanation: For an ideal transformer, V<sub>p</sub>I<sub>p</sub> = V<sub>s</sub>I<sub>s</sub> and V<sub>s</sub>/V<sub>p</sub> = N<sub>s</sub>/N<sub>p</sub> = 5. Hence I<sub>p</sub> = 5 × 2 = 10 A.
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.