Magnetic field is produced when there are moving charge carriers in a wire.

Inserting a soft iron core into an electromagnet can increase it strength.

Magnetic force always exists when there is current flowing in a conductor placed in a magnetic field.

Induced e.m.f. can exist even when there is no induced current.

The size of the induced e.m.f. of a coil in a changing magnetic field is directly proportional to the rate of change of magnetic flux linking the coil.

Eddy current induced in a conductor is always undesirable.