Name: An Elementary Study of Domestic Electric Circuits
Uploaded: 2019-07-19
Duration: 5 min 52 s
Description: The electricity we consume is produced through electromagnetic induction at power plants. In this video, we will see the journey of electricity from the powe...

Question

Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split ring in an electric motor?

Accepted Answer

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

Principle: It works on the principle that when a current-carrying coil is placed normally in a magnetic field, it experiences a torque which tends to rotate it.

Working: 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 an anticlockwise direction.
When the coil reaches the vertical position, no current flows in the coil and no force acts on the coil in this position.
(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 (clockwise) and the coil spins. The split rings or commutators help to reverse the direction of current in the circuit.

Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split ring in an electric motor?

Important Questions on Magnetic Effects of Electric Current

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