1)The armature ABCD consists of a copper wire wound on cylindrical soft-iron core.The armature can be rotated horizontal axis perpendicular to magnetic field.
2)NS is permanent horseshoe magnet with concave surfaces at poles and provides stationary magnetic field.
3) The two leads of armature coil are connected to two slip-rings S1 and S2. These slip rings are fixed on a shaft which is contact with a soft-iron core. When shaft is rotated with the help of a mechanical energy source, the armature and slip rings rotate in the same axis.
4) B1, B2 are carbon brushes. They are always in contact with slip-rings S1 and S2. These brushes B1 and B2 are connected to external circuit along resistance or load R.
Working: When the armature rotates the magnetic flux linked with it charges and electric current is induced in the coil which flows through the load resistance R. Consider the armature to be in the vertical position and let it rotate in anticlockwise direction. The wires AB move downward and CD move upward and according to Flemings right hand rule the induced current flows from B to A and from D to C. Therefore during the first half rotation of the armature, the current flows in the coil in the direction BADC. During the second half rotation the current flows in the direction CDAB. The magnitude of the induced EMF and the current also change. In this way, alternating current is produced.