
https://www.nfsa.gov.au/sites/default/files/2023-11/Chapter%201%20Block%201000%20x%20745.jpg
The maximum displacement in a wave – the largest value measured from the zero position. For example, with a pendulum, with AC the maximum current or voltage.
The amplitude of the high frequency sine wave (carrier) is changed by a low frequency wave. For example, medium-wave transmitter.