Draw the diagram of a simple electric generator. Label the following parts :
[i] Brushes [ii] Rings.

Explanation

Principle : An electric generator works on the principle of electromagnetic induction. When a coil is rotated between the magnet or when the magnet is rotated in and out of the coil , a current is induced in the coil in a direction given by Fleming.s right-hand rule.
Construction: An AC electric generator consists of a rectangular coil ABCD placed between two poles of a permanent magnet as shown in the figure. The ends of the coil are connected to rings `R_(1) and R_(2)` . The inner sides of the ring are insulated and are attached to an axle. Their outer side is made conducting and is in contact with two brushes `B_(1) and B_(2)` which are connected to a galvanometer through wires.
Working : The axle attached to the two rings is rotated such the arm AB moves up and arm CD moves down in the magnetic field produced by the permanent magnet, i.e., ABCD is rotated clockwise. Then, by Fleming.s right-hand rule, the induced currents are set up in these arms and current flows in the direction ABCD and from `B_(2) t o B_(1)` as indicated by deflection in the galvanometer.
After half a rotation, arm CD starts moving up and AB moves down. Then, the induced current flows along DCBA, and from `B_(1) t o B_(2)` externally . After every half rotation the polarity of the current changes thereby producing alternating current (AC). Thus, the device is called an AC generator.
The function of the brushes is to transmit current induced externally from coil ABCD to the external circuit.