What is the simplest relationship between the angular wavenumber k and just one of the other kinematic variables? Express your answer using only one of the other kinematic variables plus constants like π.

Answer: k = 2π / λ

Explanation: Wavenumber k (propagation number) is a measure of spatial scale. Wavenumber can be defined as the number of wavelengths per unit distance and can be expressed in terms of lambda λ, wavelength.

This definition can be mathematically expressed as

k = 2π / λ, where k is wavenumber and λ is wavelength