Alternating current dynamo is a device that converts mechanical energy into electrical energy. Its working is dependent on Faraday’s principle of electromagnetic induction.
When a closed coil is rapidly rotated in a strong magnetic field, the magnetic flux passing through it changes continuously, due to which an electric current is induced in the coil. The work done in rotating the coil is converted into electrical energy in the coil.
Its main parts are as follows-
Field magnet –
It is a powerful magnet (NS). Its function is to generate the powerful magnetic field in which the coil rotates. The lines of force of the magnetic field produced by it move from N to S.
It is a rectangular coil abcd made by wrapping a copper wire separated by a cast iron core. It has more number of copper turns. This coil is rapidly earned between the pole segments NS of the field magnet. Steam turbine, water turbine, petrol engine etc. are used to rotate the armature coil.
The two ends of the coil wrapped wire are attached to two metal rings S1 and S2 and rotate with the armature. them snake ring (Slip Rings). These rings are separated from each other and axle rod.
The spiral ring S1 S2 touches two white copper leaves b1 b2 which are called braces. This Bruce remain stationary and relate them to the external circuit in which the current is to be sent.
Let the coil abcd be moving in a clockwise direction with which arm cd is going down and ab is coming up. Fleming According to the right hand rule of , the direction of the induced current in these arms will be as shown in the figure.
Hence, the current in the external circuit will go through S2 and return through S1. When the coil passes through its vertical position, then arm ab will come down then cd will start moving up. Due to this reason ab and cd will become opposite in the direction of current. this type of stream alternating current it is said. Because the direction of current in the external circuit changes after every half cycle.
Two copper leaves b1 are attached to it b2. These lines are called Bruce. It maintains the contact of the rotating coil with the external circuit.
Raed more – What is the principle of electric motor?
Raed more – What is mercury cell?
Read in Hindi: What is the principle of electric generator?