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An e.m.f. is produced in a coil, which i...

An e.m.f. is produced in a coil, which is not connected to an external voltage source. This can be due to

A

the coil being in a time-varying magnetic field.

B

the coil moving in a time-varying magnetic field

C

the coil moving in a mnstant magnetic field.

D

the coil is stationary in external spatially varying magnetic field, which does not change with time.

Text Solution

Verified by Experts

The correct Answer is:
A, B, C
An emf is induced in a coil on account of change in magnetic flux. This is possible in only two cases given above: when the coil is in a time-varying magnetic field or when the coil is moving in a time varying magnetic field. In case of coil moving in a uniform magnetic field, do not change its orientation then flux linked with the coil does not change, so no emf will be induced but in case coil rotates or changes orientation while moving then in that case emf will be induced due to change in flux. Same is the case when the coil is stationary in a magnetic field that does not change with time but only changes with space. In this case, the coil should be moving with respect to magnetic field in order to induce emf across it, hence option (d) cannot be correct.
Options (a), (b) and (c) are correct.
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