# Amplitude

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The **amplitude** or **peak amplitude** of a wave or vibration is a measure of deviation from its central value. Amplitudes are always *positive* numbers (for example: 3.5, 1, 120) and are never *negative* (for example: -3.5, -1, -120). Amplitudes are positive because distance can only be greater than zero or equal to zero; negative distance does not exist.

The distance from the top of one peak to the bottom of another is called *peak-to-peak amplitude*. Another way to describe peak-to-peak amplitude is to say that it is the distance between the maximum positive value and the maximum negative value of a wave.

Vertical distribution of the deep water waves amplitudes is shown below:

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