When the magnetic flux linked with a circuit changes, the emf set up in the circuit is called induced emf. The current due to induced emf is called induced current.
(i) whenever the magnetic flux linked with a circuit changes, induced emf is produced.
(ii) The induced emf lasts as long as the change in magnetic flux continues.
(iii) The magnitude of induced emf (ε) is directly proportional to the rate of change in magnetic flux. Thus, if dϕ be the change in magnetic flux during the time dt then :
It is called Faraday's flux rule.
The negative sign indicates that the induced emf opposes the change in magnetic flux. In SI, the change in flux dϕ is measured in weber, dt in second and ε in volt.
Hence, volt = weber/second, i.e V = Wb/s .
