Formula Definition of the Angular Wavenumber Wavelength
$$k ~=~ \frac{2\pi}{\lambda}$$ $$k ~=~ \frac{2\pi}{\lambda}$$ $$\lambda ~=~ \frac{2\pi}{k}$$
Angular wavenumber
$$ k $$ Unit $$ \frac{\mathrm{rad}}{\mathrm{m}} $$ Angular wave number indicates the covered phase angle of a wave per meter.
Wavelength
$$ \lambda $$ Unit $$ \mathrm{m} $$ Wavelength is the smallest distance between two points of the same phase of a periodic wave. For example, the wavelength is the distance between two wave crests.