A motor is a device which electrical energy into mechanical energy. Every motor has a shaft or spindle which rotates continuously when current is passed into it. The rotation of its shaft is used to drive the various types of machines in home and industry.
Electric motor is used in electric fans, washing machines, refrigerators, mixture and grinder, electric cars and many other appliances. A common electric motor works on direct current. So, it is also called D.C. motor, which means a "Direct Current motor". The electric motor which we are going to discuss now is actually a D.C. motor.
Principle of a Motor
An electric motor the magnetic effect of current.A motor works on the principle that when a rectangular coil is placed in a magnetic field and current is passed through it, a force acts on the coil which rotates it continuously. When the coil rotates, the shaft attached to it also rotates. In this way the electrical energy supplied to the motor is converted into the machanical energy of rotation.
Construction of a Motor
An electric motor consists of a rectangular coil ABCD of insulated copper wire, which is mounted between the curved poles of a horseshoe- types permanent magnet M in such a way that it can rotate freely between the poles N and S on a shaft (The shaft is a long cylindrical rotating rod at the centre of the coil which has not been shown in picture to keep the diagram simple).
The sides AB and CD of a coil. A divice which reverses the direction of current through a current is called a commutator (or split ring).
