How is amplitude defined in relation to waves?

Amplitude is defined as the maximum displacement of a wave from its rest position. This means it measures how far the wave peaks above or dips below its equilibrium point in a medium. In the context of a sound wave, for example, the amplitude relates to the loudness of the sound; higher amplitude can be perceived as louder. Similarly, in the case of light waves, greater amplitude corresponds to increased brightness.

Understanding amplitude is crucial because it plays a significant role in determining the intensity of the wave. In contrast, the other phrases describe different aspects of wave behavior. The distance a wave travels in one cycle refers to wavelength, average speed is a measure of how fast the wave propagates through a medium, and frequency relates to how many cycles occur in a given time period. Each of these concepts is fundamental to wave physics, but they do not define amplitude.