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Describing a Wave

The Amplitude of a Wave

One way to describe a wave is by its amplitude—how high or low the wave rises or dips from its resting position. Watch the video again. Notice the height of the waves.
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All waves have an amplitude. This diagram shows how to measure the amplitude.
A labeled diagram of waves.
A line cuts across the middle of an up and down shape of a curvy line that represents waves. The line that cuts across the middle is called “the resting position.” The top part of a wave is called the “peak.” The bottom part of a wave is called the “trough.” The amplitude of one wave is shown as the distance from the line that cuts across the middle to the top of one wave, or peak. Amplitude is also measured from the middle resting position to the bottom of one wave, or the trough. The distance from resting position to peak is equal to the distance from resting position to trough.
  • The peak is the highest point of the wave.
  • The trough is the lowest point of the wave.
  • The resting position is where the material (string, rope, or water) was before the wave started.

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