Question

Describe the working of an AC generator with the help of a labelled circuit diagram. What changes must be made in the arrangement to convert it to a DC generator?

Answer 1

Working of an AC generator:
According to the Faraday's law of electromagnetic induction, whenever a conductor moves in a magnetic field EMF gets induced across the conductor. If the close path is provided to the conductor, induced emf causes current to flow in the circuit. Now, let us consider the below figure. Let the conductor coil PQRS that is placed in a magnetic field. The direction of magnetic flux will be form N pole to S pole. The coil is connected to slip rings, and the load is connected through brushes resting on the slip rings. Now, the coil is rotating clockwise, in this case, the direction of induced current can be given by Fleming's right hand rule, and it will be along P-Q-R-S. As the coil is rotating clockwise, after half of the time period, the direction of the induced current according to Fleming's right hand rule will be along S-R-Q-P. It shows that, the direction of the current changes after half of the time period that means we get an alternating current.
Conversion of AC generator to DC generator:
The split ring commutator can be used instead of the slip rings so that the direction current is not reversed every half of the cycle and thus we can get DC current that flows only in the same direction.