working of electric motor in brief...
Answers
Principle of motor : A motor works on the principle that when a rectangular coil is placed in a magnetic field and current is passed through it. A force acts on the coil which rotates it continuously.
When electric current is passed into the rectangular coil, this current produces a magnetic field around the coil.
The magnetic field of horse shoe-type magnet then interacts with the magnetic field of the coil and causes the coil to rotate continuously.
If ABCD is in horizontal position current from battery enters the coil through brush B _{ 1 }, and commutator half ring C:. The current flows in the direction ABCD
and leaves via ring and brush B _{ 2 }
The direction of current is from A to B, the direction of current is from C to D. The force on side AB of the coil is in the downward direction. Whereas the force on the side CD of the coil is in the upward direction. ABCD rotate in anti-clockwise direction.
While rotating when the coil reaches vertical position then the brushes B _{ 1 } and B _{ 2 } will touch the gap between the commutator rings and current to the coil is cut off. But the coil does not stop rotating because it has already gained momentum.
The coil CD comes on the left side and AB comes to the right side. Again they come in contact with brush B _{ 1 } Current direction is reversed.
The reversing of current in the coil is repeated after every half rotation due to which the coil continue to rotate as long as current from the batter is passed through it. The rotating shaft of electric motor can drive a large number of machines which are connected to it.
1) when the circuit is completed with a plug key or switch, the current flows in the direction.as the magnetic field is directed from the north pole to the south pole, the force on right side is downward and that on left side is upward by Fleming's left hand rule. hence, right side moves downward and left side moves upward. these forces are equal in magnitude and opposite in direction. therefore, as we observe from the right side, the loop left side and right side both the axel start rotating in anticlockwise direction...
2)after half rotation, split rings comes in contact with brushes ..right axel and left axel respectively and the current flows in all the direction .....hence, the force on left side is downward and on right-side is upward.
3)aftr every half rotation, the current in the loop is reversed nd the loop and the axel continue to rotate in anticlockwise direction.
when the current is switched off, the loop stops rotating after some tym.....