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Draw a labelled diagram of an electric motor. Explain its principle and working . What is the function of a splitring in an electric motor? |
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Answer» Solution :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 conductorplaced in a magneticfield experiencesa force whose direction is given by Fleming.sleft-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 areconnected to two halves of a split ring P and Qmounted on an axle O. The inner sides of the split ring areinsulated while their outer sides are conducting. The outersides 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 CDis reversedand hencecurrentflowsalong DCBA. Now, CD will experiencean upward force and AB a downwardforce. Thiscauses the coil and the axle to rotate half a TURN more. At each half rotation, the current reverses causing continuousrotation of the coiland the axle . The functionof split rings is to provide unidirectionalcurrent. 
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