DISPERSION

In optics, dispersion is the phenomenon that the phase velocity of a wave depends on its frequency.[1] In a prism, dispersion causes the spatial separation of a white light into spectral components of different wavelengths. Dispersion is most often described in light waves, but it may happen to any kind of wave that interacts with a medium or can be confined to a waveguide, such as sound waves. Dispersion is sometimes called chromatic dispersion to emphasize its wavelength-dependent nature.

There are generally two sources of dispersion: material dispersion and waveguide dispersion. Material dispersion comes from a frequency-dependent response of a material to waves. For example, material dispersion leads to undesired chromatic aberration in a lens or the separation of colors in a prism. Waveguide dispersion occurs when the speed of a wave in a waveguide (such as an optical fiber) depends on its frequency for geometric reasons, independent of any frequency dependence of the materials from which it is constructed. This type of dispersion leads to signal degradation in telecommunications because the varying delay in arrival time between different components of a signal "smears out" the signal in time.

DEVIATION

A deviation is a difference or the (real or metaphorical) route followed by a different choice.

Deviation can refer to:

Deviation (statistics), the difference between the value of an observation and the mean of the population in mathematics and statistics.

Standard deviation, which is based on the square of the difference.

Absolute deviation, where the absolute value of the difference is used.

Frequency deviation, the maximum allowed "distance" in FM radio from the nominal frequency a station broadcasts at.

Magnetic deviation, the error induced in compasses by local magnetic fields.

Deviationism, an expressed belief which is not in accordance with official party doctrine.

Deviation Records, a record label.

Deviant behavior, a behavior that is a recognized violation of social norms.