# Trough

A trough is the point on a wave with the maximum value of downward displacement within a wave-cycle. A crest is the opposite of a trough, so the maximum or highest point in a wave-cycle.

• On a wave at sea, the trough is the lowest point in the wave cycle, where the water displacement is furthest down from its rest position. A crest, on the other hand, is the highest point where the displacement is furthest up.
• For electromagnetic waves, which have electric and magnetic fields, a trough on either axis represents the point where the field reaches its minimum value in the downward direction. A crest represents the point of maximum value in the upward direction.
• 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.
###### References
• A trough is the point on a wave with the maximum value of downward displacement within a wave-cycle. A crest is the opposite of a trough, so the maximum or highest point in a wave-cycle.
• On a wave at sea, the trough is the lowest point in the wave cycle, where the water displacement is furthest down from its rest position. A crest, on the other hand, is the highest point where the displacement is furthest up.
• For electromagnetic waves, which have electric and magnetic fields, a trough on either axis represents the point where the field reaches its minimum value in the downward direction. A crest represents the point of maximum value in the upward direction.