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A cylindrical bar magnet lies along the axis of a circular coil. If the magnet is spun about its own axis (the cylinder axis), then:

1. A current will be induced in the coil.
2. No current will be induced in the coil.
3. Only an emf, but no current, will be induced in the coil.
4. Both an emf and a current will be induced in the coil.

Correct answer: No current will be induced in the coil.

Solution

Spinning the bar magnet about its own (symmetry) axis does not change the magnetic flux linked with the coil, because the field distribution is unchanged. With no change in flux, there is no induced emf and hence no induced current.

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