Key ideas1 of 3
Amplitude starts at equilibrium
The amplitude is the greatest displacement from the undisturbed, or equilibrium, position. Measure from the centre line to a crest or to a trough. Do not measure from a trough all the way to a crest: that distance is twice the amplitude. In the graph, the largest displacement is 2 cm. The vertical axis shows displacement, not the direction in which energy travels.
