Answer: 17.3 V.
- A 10.0 V
- B 20.0 V
- C 17.3 V
- D 14.1 V
Correct answer: C. 17.3 V
Explanation: If the flux is half its maximum value, cosθ = 1/2 so θ = 60°. The emf magnitude is E<sub>0</sub> sinθ = 20 × sin60° = 17.3 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.