One complete cycle of alternating current is generated by a _________ degree rotation of a two-pole alternator.

A complete cycle of alternating current is generated by a 360-degree rotation of a two-pole alternator because this full rotation corresponds to one complete swing of the electrical waveform, from zero to positive peak, back through zero to negative peak, and back to zero.

In a two-pole alternator, as the rotor turns, the magnetic field induces an electromotive force (EMF) that alternates in polarity. This polarity change generates the alternating current. The fundamental principle here is related to the fact that one complete cycle of AC involves both a positive and negative half-cycle, thus requiring a full rotation of 360 degrees to complete the waveform.

In other options, the other degrees are not sufficient to describe a full cycle. For example, a 180-degree rotation would result in only a half-cycle of the waveform, while 270 degrees and 90 degrees represent segments of the cycle, not the complete one. Therefore, it is this 360-degree rotational movement that fulfills the requirement for generating one full alternation in the provided context.