Question

draw a labelled diagram of an electric motor. Explain it's principle and working what is the function of split ring in electric motor?​

Answer 1

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$electric \: motor \: dc$

it is a rotating device that converts electrical energy to mechanical energy.

$principle$

when a coil carrying current is placed in a magnetic field, it experiences a force and begins to rotate in the field.

$construction$

Armature:- the armature ABCD consists of a rectangular coil of insulated copper wire.

Field magnets:- the magnetic field is supplied by two poles of permanent magnets.

Split rings:- there are two halves p and q of a metallic ring. The ends of armature coil are connected to the split rings which rotate along with the armature.

Brushes:- there are two carbon brushes X and y having constant touch with the split rings and provide contact with external circuit.

$working$

• current enters the coil ABCD from the source battery through the conducting brush X and close back to the battery through brush y.
• in arm AB of the coil current enters from a to b and in arm CD it flows from c to d that is opposite to the direction of current through a b.
• on applying Fleming's left hand rule the force acting on the arm ab pushes it downwards and force acting on CD pushes it upwards. thus the coil and axle O mounted free to turn about an Axis rotate anticlockwise.
• after half rotation q makes contact with brush X and p with brush y. the current in the coil gets reversed and flows through the patch dcba. the split rings actors commutator to reverse the current.
• the reversal of current reverse the direction of force acting on the two arms a b and c d so the arm ab was earlier pushed downwards is now pushed upwards. the arm CD earlier pushed up is pushed down. the reversing of current is repeated at each half rotation and gives rise to continuous rotation of the coil.