Question

state the principle of electric generator ? explain

Answer 1

It works based on principle of faraday law of electromagnetic induction. The far a days law states that whenever a conductor is placed in a varying magnetic field, EMF is induced and this induced EMF is equal to the rate of change of flux linkages. ... So the important elements of a generator are: Magnetic field.

Answer 2

It works on the principal of fleming's right hand rule
In this you forefinger is in the direction of magnetic field.
Your middle finger is in the direction of current induced
your thumb is in the direction of movement of conductor(motion).