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The wave equation

A wave moves energy without moving the material along with it. The wavelength is the distance between two crests, and the frequency is the number of crests passing per second. The speed is the wavelength times the frequency.

v = f\,\lambda

wave equation

T = \frac{1}{f}

period

Symbols

$v$	wave speed	m/s
$f$	frequency	Hz
$\lambda$	wavelength	m
$T$	period	s

Example

Sound at 440 Hz in air (343 m/s):

$\lambda = 343/440 \approx 0.78$ m.

The frequency is set by the source and does not change when the wave enters a new medium. Speed and wavelength do.

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Part of Foundations of Physics: Waves, sound and light.