Question

What is an electric motor? State its principle.

Answer 1

Hint:The electrical motor is a device that uses electric power to operate and it changes this electric power into rotating mechanical power. Use this principle to state the working of an electric motor.

Complete step by step answer:
The device that is used for the conversion of the electrical energy to rotational or mechanical energy is known as electric motor. Based on the power supply electric motor are of two types AC motor and DC motor. The AC motor is one that uses alternating current as its input and the DC current is one that uses Direct current as an input. Based on the AC supply the electric motor is a synchronous motor (whose rotor rotates with constant speed) and an induction motor (whose rotor has varying speed). Based on the DC supply electric motor is called DC motor. There are also some special types of motor that can work both on AC and DC power supplies, for example universal motors.

The principle on which an electrical motor works is that when a conductor that carries the current is placed in a rotating field that is magnetic in nature, the conductor then experiences a force and that force is known as the torque. The relation between the direction of the current through the conductor, the direction of the magnetic field in which the conductor is placed and the direction of the force that the conductor experiences is described by Fleming's rule of left hand. By Fleming's left hand rule, the thumb represents the direction of the force that the conductor experiences and the adjacent figure shows the direction of the field in which the conductor is placed and the third finger shows the direction of the current through the conductor.

Note:Electric generator is opposite to the electric motor in terms of operating because it converts mechanical power into electric power. The working principle of the electric generator is electromagnetic induction.