AC Generator works on which principle - Electromagnetic Induction

Today we are going to talk about AC generator and how AC generator works. You must have seen that there is an AC generator in many places. Mostly it is seen in big institutes, offices and weddings or even other programs. After all, why AC generator is found everywhere and why it is needed. Does it produce electricity or transfer electricity? If it produces electricity, how does it do that? And how much electricity can it produce at one time? And what electrical appliances can it run? 

AC Generator is a device used to generate a sinusoidally varying emf. 

AC Generator is a device that converts mechanical energy into electrical energy producing an alternating emf. The input of an AC generator is mechanical energy supplied by steam turbines, gas turbines and combustion engines. The output is alternating electrical power in the form of alternating voltage and current.

AC Generator induces an EMF or Current in a loop through the change in its Orientation or a change in its Effective area. 

Construction of AC Generator

AC Generator consists of three main parts:

1. Magnet
2. Armature with slip rings.
3.  Brushes(Carbon brushes)

It may be a permanent magnet or an electromagnet. An AC generator has two poles i.e. a magnet has a north pole and a south pole so that we have a uniform strong magnetic field.

The armature is a coil that is rectangular in shape. It is generally bounded by a soft iron core. The core is used to increase the magnetic field due to its magnetisation. 

Two ends of the coil are connected to two slip rings and attached to them are carbon brushes. Slip rings are made of metal and are isolated from each other. The Coil and ring rotate in the Magnetic field. This Axis of rotation is in the plane of the coil but perpendicular to the magnetic field. The Slip Rings slip against the brushes show that contact is maintained all the time. These Brushes are connected to the terminals, the External Circuit is connected to these terminals.

Principle of AC generator    

The AC Generators works on the principle of Faraday's law of Electromagnetic Induction. i.e. whenever the magnetic flux linked with a coil changes, an induced emf is set up in the coil, the direction of the induced current is given by the flaming right-hand rule.

Working Principle of AC Generator

The Coil is Mechanically rotated in Uniform magnetic by some means. The rotation of the coil causes the magnetic flux through it to change so that an induced EMF is set up in the coil. It generates an electric current through the galvanometer and the slip ring and brush. The Current flows out through one Brush(B1) in one-half of the revolution & through the Brush B2 in the next half in the reverse direction. This process is repeated & EMF produce is alternating in nature. Galvanometer swings between positive and negative values. This indicates that an alternating current is flowing through the galvanometer. 

Fleming's right-hand rule can be used to identify the direction of the induced current produced in the coil. Spread the thumb, first finger and middle finger of your right hand in such a way that they are perpendicular to each other. The first finger points in the direction of the magnetic field, the thumb in the direction of the conduction velocity and the middle finger in the direction of the induced current. 

The resulting induced current fluctuates in amplitude and direction at the rate of thousands of times per second. 

The EMF has its Extreme value when 'theeta = 90 degree or 270 degree' as the change in flux is greatest at these points.

EMF induced in an AC generator

Let us consider a coil(Armature) of n turns. As the coil is rotated, flux linked with the coil changes due to which EMF is induced.

Advantages of AC Generators over DC Generators

1. Through the transformer, the AC generator can be easily stepped up and down.
2. Due to the step-up functionality, the transmission link size is reduced in AC generators.
3. Loss in AC generator is relatively less than in DC machine
4. The size of the AC Generator is smaller than the DC Generator.

Applications of AC Generator 

• An AC generator is used to supply electricity to anything that requires an alternating current supply. This could be the lights and fans or the motors and air conditioning in your home.
• In the Automobiles, where they are known as alternators.
• It is used in Power generation from windmills.
• It is used in power generation from hydroelectric dams.

FAQs - Frequently Asked Questions

Q1. What is an AC Generator?

Ans- AC Generator is a device that converts mechanical energy into electrical energy producing an alternating emf.

Q2- What is the principle of an AC Generator? 

Ans- The AC Generators works on the principle of Faraday's law of Electromagnetic Induction. i.e. whenever the magnetic flux linked with a coil changes, an induced emf is set up in the coil.

Q3- What is the difference between the AC Generator and the DC Generator?

Ans- In an AC generator, the electric current periodically changes its direction regularly, resulting in alternating current. Whereas, In a DC generator, the electric current flows in only one direction.

Q4- What is Electromagnetic Induction?

Ans- Electromagnetic induction is the production of a current when the magnetic flux associated with it changes.

Q5- Which rule is used to determine the direction of induced current in an AC generator?

Ans- Fleming's Right-Hand rule is used to determine the direction of induced current in an AC Generator.