A bar magnet is held stationary inside a coil. The induced emf in the coil is
Correct answer: B. zero
- A. maximum
- B. zero
- C. half the maximum
- D. reversed in direction
Explanation
With the magnet at rest the flux linkage is constant, so its rate of change is zero and no emf is induced however strong the magnet. An emf appears only while the magnet is moving in or out, or while the field is changing. This is why a generator must keep rotating to keep producing electricity.
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About Faraday's Law
Faraday's law states that an induced electromotive force equals the rate of change of magnetic flux linkage through a circuit. Questions cover changing field, area, angle or motion, the negative sign associated with Lenz's law, and the distinction between induced emf and the current that may flow in a closed circuit.
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