The number of cycles per second that AC changes its polarity is called frequency.

• A. Measured in ohms
• B. Measured in amperes
• C. True
• D. False

Answer: (C)

Frequency is the rate at which a waveform repeats, measured in cycles per second (hertz). In AC, the voltage or current reverses polarity as the wave progresses, and one full cycle includes the switch from positive to negative and back to positive. This repetition rate—the number of complete cycles per second—is what we call frequency. So describing frequency as the number of cycles per second at which the polarity alternates fits the standard definition, even though polarity changes occur as part of each half-cycle within those cycles. Therefore, the statement is true.