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

Explanation

Construction :
(i) ABCD is rectangular coil placed between the two poles of a permanent magnt.
(ii) Arms AB of coil are attached to a ring `R_(1)` and arm C D is attached to the ring `R_(2)`.
(iii) `R_(1)` and `R_(2)` are insulated from inside and are attached to an axle.
(iv) A brush `B_(1)` touches `R_(1)` and another brush `B_(2)` touches `R_(2)`.
(v) A galvanometer is connected to `B_(1)` and `B_(2)` to show the flow and direction of current in the circuit.

Working of AC Generator :
(i) AC generator works in Fleming.s Right Hand Rule.
(ii) When coil is rotated within the magnetic field, electric current is induced in it.
(iii) Let us assume that the coil is rotating clocking in this figure. This means, AB is moving up and CD is moving down.
(iv) When AB is moving up, current flows in it from A to B.
(v) When CD is moving down, current flows in it from C to D.
(vi) After half a turn , relative positions of AB and CD change. Now, CD is moving up hence current is moving from D to C. Similarly, AB is moving down hence current is moving from B to A.
(vii) So, after every half turn the direction of current changes in this generator. This means alternating current is being generated.
Conversion of AC generator to DC generator :
For this, a split ring commutator is used in place of two separate rings. A split ring commutator maintains the direction of current in one direction and it becomes a DC generator.