How it works
These are the parts of a transverse wave, the kind that moves the medium up and down while the wave travels along. This wave diagram labels each part; print it blank to label on paper.
Read the full guide
Where to measure
The crest is a highest point and the trough a lowest point. The wavelength is one whole wave, measured crest to crest or trough to trough. The amplitude is measured from the rest position up to a crest or down to a trough, not crest to trough.
Two directions
The wave travels along, here to the right, carrying energy. The medium itself only moves up and down, at right angles to the travel, and ends where it started.
- Crest to trough is twice the amplitude, a common slip on tests.
Questions and answers
What is the amplitude of a wave?
The distance from the rest position to a crest, or to a trough. It shows how far the medium is moved from where it rests.
How do you measure wavelength?
From one crest to the next crest, or from one trough to the next trough: the length of one whole wave, parallel to the way it travels.
What is the difference between a transverse and a longitudinal wave?
In a transverse wave the medium moves at right angles to the wave's travel. In a longitudinal wave, like sound, it moves back and forth along it, in compressions and rarefactions.