File:Light dispersion conceptual waves.gif

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Light_dispersion_conceptual_waves.gif(640 × 480 pixels, file size: 1.14 MB, MIME type: image/gif, looped, 90 frames, 4.5 s)

Caption

Schematic animation of a continuous beam of light being dispersed by a prism. The white beam represents many wavelengths of visible light, of which 7 are shown, as they travel through a vacuum with equal speeds c. The prism causes the light to slow down, which bends its path by the process of refraction. This effect occurs more strongly in the shorter wavelengths (violet end) than in the longer wavelengths (red end), thereby dispersing the constituents. As exiting the prism, each component returns to the same original speed and is refracted again.

Explanation

This is a conceptual animation of the dispersion of light as it travels through a triangular prism.

In vacuum (shown in black), light of any wavelength will travel at a fixed speed, c. But light slows down in a different medium (such as glass or water), and light of shorter wavelengths (like indigo) will tend to travel slower than light of longer wavelengths (like red)

White light, represented here by a white beam, is actually made out of light of several frequencies (colors) travelling together. These basic frequencies of visible light are part of what we call visible spectrum, and it is only tiny part of the entire electromagnetic spectrum.

As white light enters a medium (in this case, the prism), each of its composing wavelengths will travel at a different speed in the new medium, and this change in speed is what bends the path in which light is travelling. This is the phenomenon we call refraction. The ratio between the speed of light in vacuum and the speed of light in a medium is what we call index of refraction, and this value is specific for a given wavelength and medium.

Since light of different wavelengths will change direction by a different amount, we will experience a division of white light in its composing spectral colors, represented here by colored waves. This is what we call dispersion.

Once the basic frequencies are separated in this animation, we can easily see the difference on their speeds. Red, with a long wavelength, passes through almost without any change, whereas indigo (with short wavelength) is left behind by all the other colors. However, this difference in speed does not hold in vacuum, and this can be seen on how all light exiting the prism will once again travel at the constant speed of light in vacuum.

This is all just an easy way of seeing it, so it is important to stress once again the fact that this model is not entirely accurate, and white light can't exist on its own (as can be misunderstood from the white beam).

Licensing

Public domain I, the copyright holder of this work, release this work into the public domain. This applies worldwide.
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File history

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Date/TimeThumbnailDimensionsUserComment
current17:09, 6 April 2010Thumbnail for version as of 17:09, 6 April 2010640 × 480 (1.14 MB)KalkiReverted to version as of 04:14, 27 February 2008
17:07, 6 April 2010Thumbnail for version as of 17:07, 6 April 2010640 × 480 (1.17 MB)KalkiReverted to version as of 03:31, 27 February 2008
04:14, 27 February 2008Thumbnail for version as of 04:14, 27 February 2008640 × 480 (1.14 MB)LucasVB
03:31, 27 February 2008Thumbnail for version as of 03:31, 27 February 2008640 × 480 (1.17 MB)LucasVB{{Information |Description=Copnceptual animation of dispersion of light in a prism. Using waves. |Source=self-made |Date=2008-02-27 |Author= Lucas V. Barbosa (aka Kieff) |Permission=Public domain |other_versions=Light_dispersion_conceptual.
04:10, 24 December 2007Thumbnail for version as of 04:10, 24 December 2007640 × 480 (348 KB)LucasVB{{Information |Description=Dispersion of light inside a prism. Now with waves. |Source=Self |Date=2007-12-24 |Author=Lucas V. Barbosa |Permission=Public Domain |other_versions=Image:Light_dispersion_conceptual.gif }}

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