Physics

# Electric Motor

The electric motor is an important indicator of industrial progress. It is a very simple and very useful machine. An electric motor is a machine by which electrical energy is converted into mechanical energy. It was invented in 1822AD by the British scientist Michael Faraday. The first commutative DC motor capable of driving an instrument was invented in 1832 by British scientist William Sturgeon. After Sturgeon’s work, American Thomas Davenport built an improved DC motor with the intention of using it for practical purposes.

## Types of Electric Motor

Electric motors are made of different types for different purposes. There are many types of motor are using in many industries. On the basis of types of electric current, these electric motor can be divided into these three categories-

### 1. AC Motor

It is conducted by ac (alternating current) current. This motor is the most used, due to which it is called the workhorse of the industries.

### 2. DC Motor

It is conducted by dc (direct current) current. DC motors are more useful where speed control is very important.

### 3. Special Motor

It is conducted by ac and dc both types of electric current. Its speed is also very good.

## Principle of the Structure of Electric Motor

When a closed coil is placed in a magnetic field and the current flows through it, it acts on it in a force field due to an electric current whose direction can be determined by Fleming’s left-hand rule. Keeps rotating continuously. Due to which electrical energy starts to be converted into mechanical energy.

### Structure of Electric Motor

There are main 5 parts of a simple electric motor:

#### 1. Power Source

Different types of motors used different types (ac or dc or both) of power sources but a simple motor usually has a DC power source. It supplies power to the motor armature or field coils.

#### 2. Field Magnet

It is a powerful powerful magnet with pole segments N and S concave in shape. The armature coil rotates in the magnetic field generated between these two poles.

#### 3. Armature Coil

It is a rectangular coil with multiple turns, which is made by wrapping it on a cast iron core with the help of copper insulated isolated wires. When the current flows, this coil field starts moving between the poles of the magnet according to Fleming’s left-hand rule.

#### 4. Split Rings

These are in the form of a ring divided into two semicircular-shaped segments. These rings are attached to the pole of the armature. The divider rings can rotate with the armature.

#### 5. Brush

A brush or carbon brush is a cuboid-shaped device made of a soft and conductive material that connects two electrical circuits. There are two leaves made of carbon metal which the divider rings touch. By connecting these brushes to two connective screws, a battery is placed between them, the electric current from one brush enters the coil and the current flows out from the other brush.

## Method of Operation of Electric Motor

When the current flows from the battery to the coil, there are two forces acting on the arms of the coil in an equal but opposite direction according to Fleming’s left-hand rule. These two forces form a bloc. Due to which the coil starts rotating in the counterclockwise direction as well as the dividing ring in it. With the help of these divider rings, the rotation of the coil is kept in the same direction. This process goes on continuously because of the rotation of the coil, its axis receives kinetic energy.

## Uses of Electric Motors

Electric motors are used in the manufacture of electric appliances, water pumps, flour mills, large machines, electric fans, railway engines, children’s electronic toys, electric trains, etc.