What components are used to transfer power to or from the rotor of alternators?

The correct choice revolves around the function of slip rings in the operation of alternators. Slip rings are essential components in alternators for transferring electrical power from the rotor to the stator and vice versa without interruption.

In an alternator, the rotor is rotating while generating a magnetic field, which induces an alternating current (AC) in the stator windings. Slip rings facilitate a continuous electrical connection to the rotor windings, allowing it to maintain the supply of current necessary for creating the magnetic field as it spins. This design enables efficient energy transfer, as the electricity generated can be continuously drawn off without the need for physical contact that would wear out over time.

While field poles are part of the magnetic circuit, and commutators are used in DC generators to convert AC generated in the rotor into a unidirectional current, they do not serve the purpose of transferring power in the context of an alternator’s operation. Hard-wired connections imply a fixed connection, which does not accommodate the rotational nature of the rotor like slip rings do. Thus, slip rings are the ideal components for this transfer of power in alternators.