Induced emf what it is

An induced emf is a voltage generated in a conductor by a magnetic effect.

Where a conductor is crossed by a magnetic field .. and the field moves or changes in strength, it produces a force on the electrons in the conductor, causing them to separate from their atoms.
This separation creates a voltage (or potential difference) within the conductor which we call an induced emf.

induced emf is the potential created due to change in magnetic flux either of its own or of another magnetic substance nearby.......

Self induction and mutual induction....refer wikipedia