Essential parts of an AC generator
The armature is a rectangular coil consisting of a large number of loops or turns of insulated copper wire wound over a laminated soft iron core or ring. The soft iron core not only increases the magnetic flux but also serves as a support for the coil
(ii) Field magnets
The necessary magnetic field is provided by permanent magnets in the case of low power dynamos. For high power dynamos, the field is provided by the electromagnet. Armature rotates between the magnetic poles such that the axis of rotation is perpendicular to the magnetic field.
(iii) Slip rings
The ends of the armature coil are connected to two hollow metallic rings R1 and R2 called slip rings. These rings are fixed to a shaft, to which the armature is also fixed. When the shaft rotates, the slip rings along with the armature also rotate.
B1 and B2 are two flexible metallic plates or carbon brushes. They provide contact with the slip rings by keeping themselves pressed against the ring. They are used to pass on the current from the armature to the external power line through the slip rings.