What does the term "frequency" refer to in the context of signals?

In the context of signals, "frequency" refers specifically to the number of occurrences of a periodic event per unit time, typically measured in hertz (Hz), which represents cycles per second. This means that if a signal or wave completes its cycle of oscillation, the frequency indicates how many times this cycle occurs within a one-second interval.

For example, a radio wave with a frequency of 100 MHz oscillates 100 million times every second. This characteristic is essential in understanding how signals are transmitted and received, as it determines the wavelength and energy of the electromagnetic waves.

The other options refer to different properties of waves or signals: the distance from one peak to another describes the wavelength, the time taken for one complete cycle indicates the period, and the amplitude relates to the strength or height of the wave. These definitions are important but do not define frequency itself.