Progressive Waves

A progressive wave is a wave that moves through a medium (or through space), carrying energy from one place to another without transferring matter. The particles of the medium oscillate about fixed positions and pass the energy along.Key terms:
Displacement (x): distance of a point from its equilibrium position, in a given direction.
Amplitude (A): the maximum displacement.
Wavelength (λ): the distance between two adjacent points in phase, such as crest to crest.
Period (T): the time for one complete oscillation.
Frequency (f): the number of oscillations per second, in hertz. f = 1/T.In one period the wave moves forward one wavelength, so its speed isv = fλWorked example: a wave on a rope has frequency 50 Hz and wavelength 0.40 m. Its speed is v = 50 × 0.40 = 20 m s^-1. Its period is T = 1/50 = 0.020 s.Two graphs are used. A displacement-distance graph is a snapshot of the whole wave at one instant, and shows the wavelength. A displacement-time graph follows one point over time, and shows the period. Both show the amplitude. Read the axis label carefully before taking a measurement from either graph.