An electric device which converts mechanical energy into electric energy is called an electric generator.
Principle: Electric generator works on the principle of electromagnetic induction. When the coil of electric generator rotates in a magnetic field, the magnetic field induces a current in this coil. This induced current then flows into the circuit connected to the coil.
Types of electric generators:
1. AC Generator
2. DC Generator
1. AC Generator: A generator which converts mechanical energy into electric energy in the form of alternating current is called AC Generator.
The main components of AC generator are as shown in figure.
1. Armature 2. Strong magnets 3. Slip rings and 4. Brushes.
Armature, strong magnets and brushes are the same as used for electric motors.
The two ends of the armature coil are connected to two brass slip rings R1 and R2. These rings rotate along with the armature coil.
a. When the armature coil ABCD rotates in the magnetic field provided by the strong magnets, it cuts the magnetic lines of forces.
b. Thus the changing magnetic field produces induced current in the coil. The direction of induced current is determined by the Flemings right hand rule.
c. The current flows out through the brush B1 in one direction in the first half of the revolution and through the brush B2 in the next half revolution in the reverse direction, this process is repeated.
d. Therefore, the induced current produced is of alternating nature. Such a current is called as alternating current.