Electric Motor

An electric motor is a rotating device that converts electrical energy to mechanical energy. Electric motor is used as an important component in electric fan, refrigerators, mixer, waterpump, washing machine etc.


Theory or Principle of Electric Motor:- 

When an electric current is passed through a coil by placing it in a magnetic field, a force acts in it. The direction of rotation of the coil is according to Fleming left hand rule.


Structure or Diagram of Elecric Motor:-  

An electric motor consists of the following parts.


1) Armature:

 An electric motor consists of a rectangular coil ABCD of insulated copper wire. The coil is placed between the two poles of a magnetic field such that the arm ab and CD are perpendicular to the direction of the magnetic field.


2) Magnets: 

This device consists of two strong magnets, between which the armature is located.


3) Commutator: 

A device that reverse the direction of flow of current through a circuit is called a commutator. In electric motor the split ring act as a commutator.


4) Brushes: 

Two brushes X and Y which are connected to the split rings p and Q respectively. And its function is to supply a constant current to the coil.


5) Battery: 

This is the source of electric current in this device.



Working: 

The coil is placed between the two poles of a magnetic field such that the arm AB and CD are perpendicular to the direction of the magnetic field. current in the coil ABCD enters from the source battery through conducting brush X and flows back to the battery through brush Y. The current in arm AB of the coil flows from Ato B and in arm CD it flows from C to D . On applying Fleming's left hand rule for the direction of force on a current carrying conductor is a magnetic field that the force acting on arm AB pushes it downwords while the force acting on arm CD pushes it upwords. 10 the coil rotate anticlockwise at half rotation Q contact with the brush X and P with brush Y. Therefore, the current in coil gets reversed and flows along the path DCBA. Thus now the arm AB of the coil pushed up and the arm CD now push down. Therefore the coil and the axle rotate half a turn more in the same direction. The reversing of the current is repeated at each half rotation,  giving rise to a continuous rotation of the coil and to the axle.