Editing Amplitude (section)

==Units==
The units of the amplitude depend on the type of wave, but are always in the same units as the oscillating variable. A more general representation of the wave equation is more complex, but the role of amplitude remains analogous to this simple case.

For waves on a [[string vibration|string]], or in a medium such as [[water]], the amplitude is a [[Displacement (geometry)|displacement]].

The amplitude of sound waves and audio signals (which relates to the volume) conventionally refers to the amplitude of the [[Sound#Sound Pressure Level|air pressure]] in the wave, but sometimes the amplitude of the [[Particle displacement|displacement]] (movements of the air or the diaphragm of a [[loudspeaker|speaker]]) is described.<ref>{{Cite web |last=Toole |first=Floyd |date=2002 |title=The Physical Nature of Sound |url=https://sbe.org/handbook/fundamentals/Audio/Audio-The_Physical_Nature_of_Sound.pdf |access-date=March 5, 2025 |website=The Society Of Broadcast Enginers}}</ref> The [[logarithm]] of the amplitude squared is usually quoted in [[decibel|dB]], so a null amplitude corresponds to −[[infinity|∞]]&nbsp;dB. [[Loudness]] is related to amplitude and [[Sound intensity|intensity]] and is one of the most salient qualities of a sound, although in general sounds it can be recognized [[Neuroscience of music|independently of amplitude]]. The square of the amplitude is proportional to the intensity of the wave.

For [[electromagnetic radiation]], the amplitude of a [[photon]] corresponds to the changes in the [[electric field]] of the wave. However, radio signals may be carried by electromagnetic radiation; the intensity of the radiation ([[amplitude modulation]]) or the frequency of the radiation ([[frequency modulation]]) is oscillated and then the individual oscillations are varied (modulated) to produce the signal.