Physics – 4.5.2 The a.c. generator | e-Consult

A simple a.c. generator typically consists of a rotating coil of wire within a stationary magnetic field. The coil is usually a rectangular piece of conducting wire, often wound into coils to increase the voltage output. The magnets are arranged around the coil, creating a magnetic field. These magnets can be permanent magnets or electromagnets.

As the coil rotates, the magnetic flux linking the coil changes continuously. This changing magnetic flux induces an electromotive force (EMF) in the coil, according to Faraday's law of electromagnetic induction. Because the direction of the magnetic flux is constantly changing with the rotation, the induced EMF is also constantly changing in magnitude and direction, resulting in an alternating current (a.c.).

Slip rings and brushes are essential for continuously supplying electricity to the rotating coil. The slip rings are conductive rings attached to the rotating coil. They provide a low-resistance path for electrical contact. Brushes, typically made of carbon, are fixed and make continuous contact with the slip rings. This allows electricity to flow into and out of the rotating coil as it spins. Without slip rings and brushes, the electrical circuit would be broken as the coil rotated, preventing the generation of a continuous a.c. current. The brushes ensure a consistent electrical connection, even as the coil rotates.