Wavelength

:For the album by Van Morrison, see Wavelength (album).

Related Topics:
Album - Van Morrison - Wavelength (album)

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The wavelength is the distance between repeating units of a wave pattern. It is commonly designated by the Greek letter lambda (?).

Related Topics:
Wave - Greek - Letter - Lambda

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In a sine wave, the wavelength is the distance between peaks:

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The x axis represents distance, and I would be some varying quantity (for instance air pressure for a sound wave or strength of the electric or magnetic field for light), at a given point in time as a function of x.

Related Topics:
Sound - Electric - Magnetic field - Light

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Wavelength ? has an inverse relationship to frequency f, the number of peaks to pass a point in a given time. The wavelength is equal to the speed of the wave type divided by the frequency of the wave. When dealing with electromagnetic radiation in a vacuum, this speed is the speed of light c, for signals (waves) in air, this is the speed of sound in air. The relationship is given by:

Related Topics:
Frequency - Electromagnetic radiation - Speed of light - Speed of sound

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lambda = rac{c}{f}

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where:

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:? = wavelength of a sound wave or electromagnetic wave

Related Topics:
Sound wave - Electromagnetic wave

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:c = speed of light in vacuum = 299,792.458 km/s ~ 300,000 km/s = 300,000,000 m/s or

Related Topics:
Light - Km/s

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:c = speed of sound in air = 343 m/s at 20 °C (68 °F)

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:f = frequency of the wave

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For radio waves this relationship is approximated with the formula: wavelength (in metres) = 300 / frequency (in megahertz).

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When light waves (and other electromagnetic waves) enter a medium, their wavelength is reduced by a factor equal to the refractive index n of the medium but the frequency of the wave is unchanged. The wavelength of the wave in the medium, λ' is given by:

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:

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lambda^prime = rac{lambda_0}{n}

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where:

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:?0 is the vacuum wavelength of the wave

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Wavelengths of electromagnetic radiation, no matter what medium they are travelling through, are usually quoted in terms of the vacuum wavelength, although this is not always explicitly stated.

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Louis de Broglie discovered that all particles with momentum have a wavelength associated with their quantum mechanical wavefunction, called the de Broglie wavelength.

Related Topics:
Louis de Broglie - Momentum - Quantum mechanical - Wavefunction - De Broglie wavelength

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