Physics
A bar magnet is kept along the axis of a circular coil as shown in the figure given below. The magnet is rotated (i) about its own axis and (ii) about an axis perpendicular to the length of the magnet. The induced emf is generated at the terminals of the coil in :
- (i) only
- (ii) only
- none of the cases
- both the cases
Electro-Magnetism
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Answer
(ii) only
Reason — Induced emf is produced only when there is a change in magnetic flux through the coil.
When the magnet is rotated about its own axis (i), the magnetic field linked with the coil does not change, so no emf is induced.
However, when it is rotated about an axis perpendicular to its length (ii), the magnetic flux through the coil changes continuously, thus inducing an emf.
Hence, the induced emf is generated at the terminals of the coil in (ii) only
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