Answer: B x A x cos(theta).
- A B x A
- B B x A x cos(theta)
- C B x A x sin(theta)
- D B/A
Correct answer: B. B x A x cos(theta)
Explanation: Magnetic flux phi = B x A x cos(theta) where theta is angle between B and the area normal vector.
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.