Question

What is an electric motor? With the help of a labelled diagram, describe the working of a simple electric motor.

Accepted Answer

An electric motor is a device which converts electrical energy into mechanical energy.

Working:
(i) When current flows through the coil, arms AB and CD experience a force. According to Fleming’s left-hand rule, arm AB of the coil experiences a force in the downward direction. Similarly, arm CD of the coil experiences a force in the upward direction. Two equal and opposite forces constitute a couple and hence the coil will rotate in anticlockwise direction.
(ii) When the coil reaches the vertical position, no current flows in the coil and no force acts on the coil in this position.
(iii) Now coil rotates further and side AB is moved on the right, with its commutator segment touching the right-hand brush so it has a downward force acting it. Similarly, side CD has an upward force on it. Thus, the couple always acts in the same direction (anti-clockwise) and the coil spins.
(iv) The split rings or commutators help to reverse the direction of current in the circuit.

A labelled diagram of an electric motor is shown below:

Lakhmir Singh and Manjit Kaur Solutions for Chapter: Magnetic Effect of Electric Current, Exercise 14: Long Answer Type Questions

Lakhmir Singh Physics Solutions for Exercise - Lakhmir Singh and Manjit Kaur Solutions for Chapter: Magnetic Effect of Electric Current, Exercise 14: Long Answer Type Questions

Questions from Lakhmir Singh and Manjit Kaur Solutions for Chapter: Magnetic Effect of Electric Current, Exercise 14: Long Answer Type Questions with Hints & Solutions

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