Use the formula: wavelength = wave speed ÷ frequency
Write it as: λ = v / f
Measure or identify the wave speed
Measure or identify the frequency
Divide the wave speed by the frequency
Use meters for wavelength, meters per second for speed, and hertz for frequency
For light waves in a vacuum, use: λ = c / f
For sound waves, use the speed of sound in the medium
For waves with period, use: wavelength = wave speed × period
Write it as: λ = vT