Which concept defines the number of cycles per second in an AC signal?

• A. Frequency
• B. Relative motion
• C. Inductance/Inductor
• D. Current

Answer: (A)

Frequency is the number of cycles a periodic signal completes each second. In an AC signal, the waveform repeats itself, and frequency tells you how many times that repetition occurs per second. Measured in hertz, frequency is the reciprocal of the period—the time for one complete cycle. For example, a wave that repeats 60 times each second has a frequency of 60 Hz. This concept explains how often the signal cycles, which is fundamental to understanding how AC behaves in circuits, radios, and power systems. Relative motion describes speed of movement, inductance is a property that resists changes in current, and current is the rate of charge flow; none of these describe how often the waveform repeats per second.