What is represented by the frequency of an AC sine wave?

The frequency of an AC sine wave is defined as the number of complete cycles that occur in one second. This characteristic is measured in hertz (Hz), where one hertz represents one cycle per second. In the context of alternating current (AC), the frequency is critical because it determines how quickly the current alternates direction and influences the performance of electrical devices. For instance, standard frequencies like 50 Hz or 60 Hz are commonly used in household power supplies, and understanding this frequency helps in the design and function of electrical systems.

The other options represent different concepts related to AC waveforms but do not define frequency. The maximum voltage level pertains to the height of the sine wave, the time for one complete cycle indicates the period (which is the inverse of frequency), and the RMS voltage value represents the effective value of an AC waveform. Each of these components plays a vital role in understanding AC systems, but they do not specifically capture the essence of what frequency signifies.