What is the definition of amplitude?

The correct definition of amplitude is the greatest distance from the midpoint of the wave. Amplitude measures how far a wave moves from its rest position (the midpoint), indicating the maximum extent of its displacement, whether upwards or downwards. In practical terms, it represents the 'strength' or 'intensity' of the wave; for example, in sound waves, a larger amplitude corresponds to a louder sound.

The midpoint is crucial because it serves as a reference point, ensuring the measurement is consistent, regardless of whether the wave is oscillating above or below this line. Thus, defining amplitude in this way captures the essence of a wave's magnitude in a clear and accurate manner, making it foundational to understanding wave behavior in various contexts, such as sound, light, and water waves.