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?

Explanation

An electric motor is an electrical device that converts electrical energy into mechanical energy which can be used to do work.
Principle : A current carrying conductor placed in a magnetic field experiences a force whose direction is given by Fleming.s left-hand rule.
Construction : An electric motor consists of a rectangular coil ABCD of insulated copper wire placed between the two poles of a permanent magnet. The two ends of the coil are connected to two halves of a split ring P and Q mounted on an axle O. The inner sides of the split ring are insulated while their outer sides are conducting. The outer sides of the split ring are connected to a circuit consisting of a battery and a plug key through two brushes X and Y whose position is fixed.
Working : When current is applied, it flows along ABCD . Thus, according to Fleming.s left-hand rule, arm AB experiences an upward force while arm CD experiences a downward force. These two equal and opposite forces constitute a couple and cause the coil to rotate in anti-clockwise direction. At half rotation, position of AB and CD is reversed and hence current flows along DCBA. Now, CD will experience an upward force and AB a downward force. This causes the coil and the axle to rotate half a turn more. At each half rotation, the current reverses causing continuous rotation of the coil and the axle . The function of split rings is to provide unidirectional current.