Wavelength

As wavelength (Greek lambda ) is the smallest distance between two points of the same phase of a wave is called. Here, two points have the same phase if they have the same displacement (elongation ) and the same direction of motion over time. The wavelength is the spatial analogue of the period.

It is

Where c is the propagation speed (or the phase velocity ), and f is the frequency of the wave. The propagation speed is therefore the product of the wavelength and frequency.

Wavelength of sound waves in the medium

The human ear is sensitive in a wavelength range of at most about 17 mm to 21 m at a speed of sound in the medium air of c = 343 m / s ( corresponding to frequencies of about 16 hertz to 20,000 hertz ). Some animals can also be smaller or larger wavelengths perceive.

Wavelengths of visible light: colors

The human eye is sensitive to a wavelength range of about 380 nm ( violet) to 780 nm ( red). Bees see also shorter wavelength radiation ( ultraviolet), but can not perceive red light.

For more information on color perception of the eye can be found in the article color.

Wavelength of electromagnetic waves in the medium

For the wavelength in a medium where:

It is the speed of light in vacuum, the relative permittivity and the magnetic permeability of the medium. If the electromagnetic wave traversing a medium whose refractive index is greater than, the wavelength is reduced and speed of propagation, depending on the refractive index. But the frequency does not change. Is the wavelength in the medium

Wherein the vacuum -wavelength of the wave.

Wavelengths of electromagnetic radiation are usually expressed as a vacuum wavelength, but which is expressed explicitly.

De Broglie wavelength

Louis -Victor de Broglie discovered that all particles can be described by matter waves. The wavelength of such a material is called the shaft de Broglie wavelength, and depends on the momentum of the particle p. For a relativistic particle, the wavelength can be determined with the following equation:

Here, h is Planck's constant, c is the speed of light, m is the mass and v is the velocity of the particle.