How this calculator works
Frequency counts how often the wave repeats at a point. Propagation speed links these quantities. Vacuum light uses the exact speed 299792458 m/s. The sound presets are approximate values for air and fresh water at 20 C, not universal material constants. Use a custom speed for another temperature, composition or medium. Spatial frequency in cycles per metre differs from angular wavenumber by 2 pi.
Formula
v = f lambda; T = 1/f; spatial frequency = 1/lambda; angular wavenumber k = 2 pi/lambda.
Worked example
A 12 m/s wave with wavelength 3 m has frequency 4 Hz and period 0.25 s. A wave travelling at 12 m/s with frequency 3 Hz has wavelength 4 m and spatial frequency 0.25 cycles/m.
Advertisement
Frequently asked questions
Does frequency change when a wave enters another medium?
For a stationary boundary and source, frequency stays the same while speed and wavelength change.
Can I use sound speed for light?
Choose a speed appropriate to the actual wave. Mechanical and electromagnetic waves propagate by different mechanisms.
Is wavenumber always 1 divided by wavelength?
Some references use that spatial frequency, while others define angular wavenumber as 2 pi divided by wavelength. Both are labelled here.