What is defined as one complete positive and one complete negative alternation of a current or voltage?

• A. One half cycle
• B. Frequency unit
• C. One complete positive and one complete negative alternation of a current or voltage
• D. Amplitude of the waveform

Answer: (C)

In alternating current, a full cycle is made up of one positive half-cycle and one negative half-cycle. This is the complete oscillation where the waveform goes from positive direction through zero to the negative direction and back again. The two halves are equal in a pure sine wave, and together they define the period of the waveform. A single half-cycle is only part of the motion, so it isn’t a full cycle. Frequency measures how many of these cycles occur each second, while amplitude refers to the peak value of the voltage or current, not the number of half-cycles. So the described idea corresponds to a full cycle of the AC waveform.