Period T

The period of a wave is the time taken for one wave to be produced or the time for one complete oscillation or vibration.

It is also the time taken for one whole wave to pass a point.

Period is measured in seconds.

Wave speed equation

The speed of a wave is related to its frequency and wavelength, according to the equation:

wave~speed~(v) = frequency (f) \times wavelength (\lambda)

v = f~ \lambda


v = wave speed in metres per second, m/s

f = frequency in hertz, Hz

\lambda (lambda) = wavelength in metres, m

Formula triangle demonstrating v equals f times lambda. V at the apex of triangle, f in bottom-left corner and lambda in bottom-right. Also demonstrates f equals v over lambda, lambda equals v over f.A formula triangle for the wave speed equation

All waves, including sound waves and electromagnetic waves, follow this equation.

It should be noted that some particular waves have their own specific speeds:

  • the speed of light and all of the electromagnetic spectrum in a vacuum is 300,000,000 m/s or 3×108 m/s
  • the speed of sound in air is often taken to be 340 m/s.