# Dictionary:Κ/zh

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This page is a translated version of the page Dictionary:Κ and the translation is 17% complete.
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{{#category_index:K|κ}} ${\displaystyle \kappa }$ Kappa.

${\displaystyle {\text{wavenumber}}={\frac {1}{\lambda }}=k={\frac {\kappa }{2\pi }}={\frac {f}{V}}}$

where ${\displaystyle \lambda }$=wavelength, f=frequency, and V=velocity. Thus ${\displaystyle \kappa }$ is to wavenumber in the spatial sense as angular frequency ${\displaystyle \omega }$ is to frequency f in the time sense. Confusingly, both ${\displaystyle \kappa }$ and k are often called wavenumber, i.e., some authors use ${\displaystyle \kappa ={\frac {1}{\lambda }}}$ instead of the above.

2. Seismic usage often implies apparent wavenumber ${\displaystyle k_{a}={\frac {1}{\lambda _{a}}}}$, ${\displaystyle \lambda _{a}}$ being the apparent wavelength and Va the apparent velocity. If this definition is used, ka varies with the angle between the raypath and the line of measure (the line of the spread, usually).