A cycle on an AC sine wave is defined by a complete positive and negative alteration.

• A. One positive and one negative alteration
• B. A complete peak-to-peak measurement
• C. A single half-cycle
• D. A zero-crossing event

Answer: (A)

A cycle in an AC sine wave is the full repetition unit, consisting of both a positive half and a negative half. Imagine the waveform rising from zero to a positive peak, crossing zero again, dropping to a negative peak, and returning to zero. That complete sequence—the positive part followed by the negative part—defines one cycle. The peak-to-peak distance relates to how far the peaks are from each other (amplitude range), not to what makes up a single cycle. A half-cycle would include only the positive or the negative portion, and a zero-crossing is just a moment within the cycle, not the whole cycle.