Terminology

 Term Symbol Definition Displacement The displacement measures the change in some quantity as a wave passes a particular point. For longitudinal waves this quantity may be the pressure while for transverse waves it may be the actual height of the wave. The displacement is the taken relative to mean or average displacement. Amplitude The maximum displacement from the mean position. If the wave does not lose any energy as it moves, the displacement is constant. Period The time taken for one complete oscillation in the case of a standing wave, or the time taken for one complete wave to pass a fixed point in the case of a fixed wave. Frequency The number of oscillations per second. It is measured in Hertz (Hz). Note that that it is not necessary for the frequency to be a whole number eg 2.5 Hz is a possible frequency. Note that Wavelength The shortest distance between two crests, or more accurately, between two points with the same phase. Usually measured in metres. Wave speed The speed with with a wave passes a stationary observer. Usually measured in m/s. Note that