dispersion (redirected from Dispersive power)

dispersion /dis·per·sion/ (-per´zhun)

1. the act of scattering or separating; the condition of being scattered.

2. the incorporation of the particles of one substance into the body of another, comprising solutions, suspensions, and colloid systems; used particularly for an unstable colloid system. See colloid (2).

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dis·per·sion (d-spûrzhn)

n.

1. The act or process of dispersing.

2. The state of being dispersed.

3. Disperse system.

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dispersion

[dispur′shən]

the scattering or dissipation of finely divided material, as when particles of a substance are scattered throughout the volume of a fluid. Examples include colloids and gels, such as egg white, soap, and gelatin, which consist of large molecules or clumps of molecules that are able to attract and hold large numbers of water molecules.

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dispersion

1. the act of scattering or separating; the condition of being scattered.

2. the incorporation of one substance into another.

3. a colloid solution.

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dispersion

Phenomenon of the change in velocity of propagation of radiation in a medium, as a function of its frequency, which causes a separation of the monochromatic components of a complex radiation. All optical media cause dispersion by virtue of their variation of refractive index with wavelengths. Dispersion is specified by the difference in the refractive index of the medium for two wavelengths. The difference between the blue F (486.1 nm) and the red C (656.3 nm) spectral lines is called the mean dispersion, i.e. n_F − n_C. Dispersion is usually represented by its dispersive power ω or relative dispersion which is equal to the mean dispersion divided by the excess refractive index of the helium d (587.6 nm) spectral line (n_d − 1), often called the refractivity of the material,

ω = n_F − n_C/n_d − 1

The reciprocal of the dispersive power is called the Abbé's number or constringence (Fig. D8). See aberration longitudinal chromatic; achromatic axis; Fraunhoffer's lines; achromatic prism.

Fig. D8 Dispersion of a white beam of light by a prism