Rest position – the undisturbed position of particles when they are not vibrating.
Displacement – the distance that a certain point in the medium has moved from its rest position.
Peak – the highest point above the rest position.
Trough – the lowest point below the rest position.
Amplitude – the maximum displacement of a point of a wave from its rest position.
Wavelength – distance covered by a full cycle of the wave. Usually measured from peak to peak, or trough to trough.
Time period – the time taken for a full cycle of the wave. Usually measured from peak to peak, or trough to trough.
Frequency – the number of complete waves passing a point each second.
Wavelength can be defined as “the distance between two adjacent points in a wave that move in phase (or in step)”. Frequency can be defined as “the number of cycles of a wave that occur in one second”.