A crest is a point on a wave with the maximum value of upward displacement within a wave-cycle. A trough is the opposite of a crest, so the minimum or lowest point in a wave-cycle.
- On a wave at sea, the crest is a point where the displacement of water is at a maximum. A trough is the opposite of a crest, so a trough is a point where the displacement of the water is at a minimum.
- In the case of an electromagnetic wave which has an electric and a magnetic axis, a crest on either axis refers to maximum displacement in the positive direction whilst a trough refers to minimum displacement.
- Wavelength refers to a complete wave-cycle from one crest to the next, or one trough to the next.
- Frequency refers to the number of wave-cycles that pass a given point in a given amount of time.
- The amplitude of a wave is a measurement of the distance from the centre line (or the still position) to the top of a crest or to the bottom of a corresponding trough.
- Amplitude is related to the energy a wave carries. The energy a wave carries is related to frequency and amplitude. The higher the frequency, the more energy, and the higher the amplitude, the more energy.
Related diagrams
Each diagram below can be viewed on its own page with a full explanation.
