Question

with a neat labelled diagram, explain the construction and working of an electric motor

Answer 1

Working
1 let coil ABCD be in horizontal position . when the key is closed the current flows in the coil ABCD through brush X and flows back to battery through the brush Y

2 no force act on arm BC and AD as they are parallel to magnetic field . Arm AB experiences a force in downward direction and CD experiences an equal force in upward direction. The direction of force is obtained by applying Fleming's left hand rule . this causes the coil to rotate in the anticlockwise direction .

3 when the coil rotates is in vertical position the brushes lose contact with the rings and current stop flowing but the coil does not stop due to inertia of motion

4 when the coil rotates the rings change their position and come in contact with opposite brushes

5 this reverses the direction of current through the coil but the direction of current on the right hand side of the coil remains the same
so the force on right hand side is always upward and their force on left hand side is always in downward direction .Thus the coil continuous to rotate in anticlockwise direction

Answer 2

In a basic DC motor, an armature is placed in between magnetic poles. If the armature winding is supplied by an external DC source, current starts flowing through the armature conductors. As the conductors are carrying current inside a magnetic field, they will experience a force which tends to rotate the armature.