Correct option is C
Explanation:
The commutator in a DC machine serves a critical role in the operation of both DC motors and DC generators:
In a DC Motor: The commutator converts the alternating current (AC) induced in the armature windings into direct current (DC) at the terminals. As the armature rotates within the magnetic field, the current induced in the windings is alternating in nature. The commutator reverses the connections at the right moments to ensure that the current supplied to the external circuit remains unidirectional.
In a DC Generator: The commutator converts the AC generated in the armature windings into DC. As the armature coils rotate, they generate an alternating electromotive force (EMF). The commutator rectifies this alternating EMF into a direct current output by mechanically switching the connections of the armature windings to the external circuit.
Thus, the commutator essentially acts as a mechanical rectifier, converting AC generated within the machine into DC and vice versa, depending on whether the machine is operating as a motor or a generator. Therefore, option (c) is the correct answer as it accurately describes the dual function of the commutator.
