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?

(N/A) An electric motor converts electrical energy into mechanical energy.
It works on the principle of the magnetic effect of current. $A$ current-carrying coil rotates in a magnetic field. The following figure shows a simple electric motor.
When a current is allowed to flow through the coil $MNST$ by closing the switch,the coil starts rotating anti-clockwise. This happens because a downward force acts on length $MN$ and at the same time,an upward force acts on length $ST$. As a result,the coil rotates anti-clockwise.
Current in the length $MN$ flows from $M$ to $N$ and the magnetic field acts from left to right,normal to length $MN$. Therefore,according to Fleming's left-hand rule,a downward force acts on the length $MN$. Similarly,current in the length $ST$ flows from $S$ to $T$ and the magnetic field acts from left to right,normal to the flow of current. Therefore,an upward force acts on the length $ST$. These two forces cause the coil to rotate anti-clockwise. After half a rotation,the position of $MN$ and $ST$ interchange. The half-ring $D$ comes in contact with brush $A$ and half-ring $C$ comes in contact with brush $B$. Hence,the direction of current in the coil $MNST$ gets reversed.
The current flows through the coil in the direction $TSNM$. The reversal of current through the coil $MNST$ repeats after each half rotation. As a result,the coil rotates unidirectionally. The split rings help to reverse the direction of current in the circuit. These are called the commutator.