Question

(a) What is an electric motor? With the help of a labelled diagram, describe the working of a simple electric motor.
(b) What are the special features of commercial electric motors?

Answer 1

(a) An electric motor is a device that converts electrical energy into mechanical energy.

Diagram: Electric motor

Working of an electric motor:

An electric motor works on the principle of magnetic effect of electric current. In an electric motor, a rectangular coil ABCD in placed between two magnets in poles N and S. Now, current is passed through it continuously. When current is passed into the coil, it produces a magnetic field around it. The two magnetic fields interact and cause the coil to rotate. When the coil rotates, the shaft attached to it also rotates. In this way, electrical energy supplied to the motor is converted into mechanical energy.

(b) Special features of commercial electric motors are:

(i) The coil is wound on a soft iron core; therefore, the strength of magnetic field increases.

(ii) The coil contains large number of turns of insulated copper wire.

(iii) A powerful electromagnet is used in place of permanent magnet.