A sine wave, with its wavelength
A wavelength is the length of the shortest repeating part of a "sine wave". All waves can be formed by adding up sine waves. That is, every wave is a total of sine waves, which may be identified by Fourier analysis.
Examples of waves
Waves are everywhere. Examples of waves include:
"Length" of a sine wave
The sine wave has a pattern that repeats. The length of this repeating piece of the sine wave is called the wavelength. The wavelength can be found by measuring the length or distance between one peak of a sine wave and the next peak. The wavelength can be found in many other ways too.
There are other properties of waves and sine waves, such as their frequency, amplitude, phase, and speed.
A symbol used for wavelength most often is the Greek letter lambda (λ).
Images for kids
A standing wave (black) depicted as the sum of two propagating waves traveling in opposite directions (red and blue)
Wavelength is decreased in a medium with slower propagation.
Separation of colors by a prism (click for animation)
Various local wavelengths on a crest-to-crest basis in an ocean wave approaching shore
A sinusoidal wave travelling in a nonuniform medium, with loss
A wave on a line of atoms can be interpreted according to a variety of wavelengths.
A propagating wave packet
Pattern of light intensity on a screen for light passing through two slits. The labels on the right refer to the difference of the path lengths from the two slits, which are idealized here as point sources.
Diffraction pattern of a double slit has a single-slit envelope.