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?
Electric Motor looks like
Principle of an electric motor
An electric motor works on the principle that
when a rectangular coil is placed in a magnetic field and a current is passed through it,
a force acts on the coil which rotates it continuously
Working of an electric motor
When battery is switched on, current flows through coil AB from A to B,
and Magnetic Field is from North to South...
So, by Fleming's left hand rule, downward force is applied on AB.
Similarly, upward force is applied on CD.
Thus, the coil rotates with AB moving down and CD moving up
Now, as the coil rotates, the rings spin with it
When coil becomes parallel to the magnetic field,
the brushes X and Y touch the gap between the rings
and the circuit breaks
And due to inertia, the ring keeps moving... so the opposite end of the ring is now connected the positive end of wire
Split ring P is connected to coil CD and split ring Q is connected to coil AB.
Which reverses the direction of current in the circuit.
Now, when CD is on left side and AB is on right side..
Current in CD becomes reversed i.e. from D to C.
So, force on CD is downwards and force on AB is upwards
Thus, the coil keeps rotating
This reversing of electric current happens every half rotation
and the coil continues to rotate until the battery is switched off
Function of Split Ring
Function of the split ring is to reverse the flow of current and make coil and axle rotate in the same direction.