generator

Machine that produces electrical energy from mechanical energy, as opposed to an electric motor, which does the opposite. A simple generator (known as a dynamo in the UK) consists of a wire-wound coil (armature) that is rotated between the poles of a permanent magnet. As the coil rotates it cuts across the magnetic field lines and a current is generated. A dynamo on a bicycle is an example of a simple generator.

The current generated can be increased by using a stronger magnet, by rotating the armature faster, or by winding more turns of wire onto a larger armature.

The movement of the wire in the magnetic field induces a current in the coil by electromagnetic induction, which can be fed by means of a commutator as a continuous direct current into an external circuit. Slip rings instead of a commutator produce an alternating current, when the generator is called an alternator.