dispersion, in chemistry, mixture in which fine particles of one substance are scattered throughout another substance. A dispersion is classed as a suspension, colloid, or solution. Generally, the particles in a solution are of molecular or ionic size; those in a colloid are larger but too small to be observed with an ordinary microscope; those in a suspension can be observed under a microscope or with the naked eye. A coarse mixture (e.g., sand mixed with sugar) is usually not thought of as a dispersion.

dispersion, in physics: see spectrum.

Any phenomenon associated with the propagation of individual waves at speeds that depend on their wavelengths. Wavelength determines the speeds at which waves travel through media. This variation in speed causes radiation to separate into components that have different frequencies and wavelengths. For example, when a beam of white light is sent through a glass prism, refraction causes the beam to disperse into an array of its component colours of light, producing a rainbowlike effect.

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