Question

what is the principle of AC generator

Answer 1

As a matter of fact, the principle of AC generator is the same to direct-current generator. The basic principle of a generator is to convert motion into electricity. Providing this motion requires that either a magnetic field is generated and a wire coil is rotated within it, or a magnetic field is rotated within a stationary coil. The turning of a coil in a magnetic field produces motional emfs in both sides of the coil which add. Since the component of the velocity perpendicular to the magnetic field changes sinusoidally with the rotation, the generated voltage is sinusoidal or AC.

Answer 2

It works on the principal that when a straight conductor is moved in a magnetic field then current is induced in the conductor i.e Electromagnetic induction.