Which component differentiates a DC generator from an AC generator?

A DC generator is characterized by the use of a commutator and brushes, which are essential components for converting the alternating current (AC) generated within the machine to direct current (DC). The commutator is a mechanical switch that periodically reverses the connection of the coil to the external circuit, ensuring that the output remains in one direction, which is the defining feature of DC power. The brushes make physical contact with the rotating commutator to transfer the electrical current to the external circuit.

In contrast, an AC generator does not use a commutator; instead, it employs slip rings that maintain continuous contact while allowing for the alternating current generated in the windings to be transmitted to the output circuit. This fundamental difference in design reflects the operational principles used in each type of generator, making the commutator and brushes crucial components that distinguish a DC generator from its AC counterpart.