Final answer:
A DC generator or dynamo uses brushes and a commutator to convert mechanical energy into pulsed DC electrical energy. Commutators reverse the current direction in the coil each half turn, while brushes enable current to flow to the external circuit.
Step-by-step explanation:
The type of generator that has brushes riding on a commutator to carry the current to an external circuit is known as a DC generator, or a dynamo. These generators convert mechanical energy into electrical energy, using a commutator to produce direct current (DC). The commutator is a rotary switch that reverses the direction of current in the coil each half turn to provide a pulsed DC output. The brushes maintain electrical contact with the commutator as it spins, thus enabling current to flow through an external circuit.
Like motors, which convert electrical energy into mechanical work, generators and motors share similar construction principles. In both devices, a coil is rotated in a magnetic field, and a mechanical shaft is involved in the energy conversion process. However, in generators, the shaft is rotated mechanically to produce an electric current, whereas in motors, the current is supplied to create rotational motion of the shaft.