#### • Class 11 Physics Demo

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# Difference between AC and DC Generator

Generator is a device which generates power or energy. As we know that the energy can neither be created nor be destroyed and hence the generator can transform the energy from one form to another and hence in turn produces energy in the desired form. The electric generator generates electricity by transforming mechanical energy to the electric energy. Some of the different types of electric generators are as follows:
• Water turbine
• Internal combustion engine
• Wind turbine
The water turbine converts the mechanical energy produced by waterfall to the electric energy. The falling water imparts the potential energy to the turbine and rotates it. Due to this rotation the electric energy is produced.

Wind turbine converts the mechanical energy produced by the wind to the electric energy. The free flowing wind has potential energy which is imparted to the turbine which rotates it and hence the transferred mechanical power is converted to the electric energy.

The generators are also categorically divided into two types with respect to the type of current produced by them;
• DC Generators
• AC Generators
DC generator:

It is a machine which uses the principle of Faraday's Laws of Electromagnetic Induction. When a conductor cuts a magnetic field, a magnetic field of varying nature is generated. This varying magnetic field generates a current to flow in the current whose direction is opposite to that of the varying field and hence in turn it opposes the vary creator of itself. In this generator the coil or conductor is rotated in the field to produce current.

AC Generator:

It is similar to that of the DC generator which uses varying magnetic field to produce the current. In actual scenario either a conductor is rotated in the varying magnetic field or a varying magnetic field is created around a stationary conductor. In this generator the magnet is moved while the conductor is fixed to produce the current.

Difference between the AC and DC generator:
• In the AC generators the current changes its direction in each rotation and hence the average current output is zero. In the DC generators the current never changes direction and is always in the one direction and hence the average current output is equal to the magnitude of current produced by it.
• An AC generator may be easily converted to the DC generator by using a bridge rectifier in the output to rectify the AC to produce DC.
• DC generator uses half ring collector to output the current while the AC generator uses two ring brushes to conduct the current output.
• The DC generator can also be made by using two diode at the output of the AC generator so that in each cycle one of the two diodes conducts and the current is outputted. The DC so produced is pulsating DC.
• In AC generators the coil is fixed while the magnet is movable while in DC generators the coil rotates in the fixed magnetic field.