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

Answer

  1. The coil being in a time varying magnetic field.
  2. The coil moving in a time varying magnetic field.
  3. The coil moving in a constant magnetic field.
Solution:
Key concept: As we know whenever the number of magnetic lines of force (magnetic flux) passing through a circuit changes, an e.m.f is produced in the circuit called induced e.m.f. The induced e.m.f persists only as long as there is a change or cutting of flux.
In this problem, magnetic flux linked with the isolated coil changes when the coil is placed in the region of a time varying magnetic field, the coil moving in a constant magnetic field or in time varying magnetic field.
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