An AC generator is a machine by which mechanical energy is
transformed into AC electrical energy.
The angle between the field
and normal to the coil changes continuously when the armature coil is rotated
in the magnetic field. Therefore, magnetic flux linked with the coil changes.
An emf is induced in the coil.
The flux,
\[\phi =N(\vec{B}\cdot \vec{A})=NABcos\theta =NABcos\ \omega t\]
Where N is the number of turns in
the coil, A is the area enclosed by each of the coil, B is the strength of the
magnetic field and ω is the angular velocity of the coil.
The emf from Faraday’s Law,
.
\[E =-\frac{d\phi }{dt}=NBA\omega sin\ \omega t\]
This is the EMF Supplied by the A.C. generator
