[Member (365WT)]answers [Chinese ]  Time :20191115  The phase velocity or phase velocity of a wave, or simply the phase velocity, refers to the velocity at which the phase of the wave travels in space. In other words, the phase of any frequency component of the wave is transmitted at this velocity. You can pick any particular phase of the wave to observe (for example, a crest), where it will travel at the phase velocity. The phase velocity can be expressed by the frequency f of the wave and the wavelength λ, or the relationship between the angular frequency ω and the wave vector k.
Vp=fλ=ω/k
Phase velocity can be used not only to describe light waves, but also to describe elastic waves. 
