## Longitudal waves - sound waves

Hi.
I am looking for correct mathematical definition of longitudal wave im 3-D
if somebody will help me with some link or explanation it will be great.
Another thing: when I have a point source of waves i see that wavenumber changes from one point to point, is it wright?
thanx

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 Recognitions: Homework Help Science Advisor Longitudinal means that the wave number is parallel to the displacement. Also, please elaborate on what you mean when you say you see the wavenumber changes from point to point with a point source.
 Recognitions: Science Advisor The wavenumber is a term generally only used in 1 dimension. In general, we use a wave[/I]vector[I] to specify, not just the wavelength of the wave, but also the direction of propagation. Since, for a point source, the direction of propagation varies with position, the wavevector must too, vary with position. The magnitude of the wavevector however does not vary so long as the wavelength of the source remains constant. Claude.