refraction (redirected from refractional)

re·frac·tion  (r-frkshn) n. 1. The turning or bending of any wave, such as a light or sound wave, when it passes from one medium into another of different optical density. 2. Astronomy The apparent change in position of celestial objects caused by the bending of light rays entering Earth's atmosphere. 3. Medicine a. The ability of the eye to bend light so that an image is focused on the retina. b. Determination of the refractive characteristics of the eye. re·fraction·al, re·fractive adj. re·fractive·ly adv. re·fractive·ness, refrac·tivi·ty (rfrk-tv-t) n.

refraction refraction of light; i: angle of incidence; r: angle of refraction

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refraction

Noun

Physics

1. the change in direction of a wave, such as light or sound, in passing from one medium to another in which it has a different velocity

2. the amount by which a wave is refracted

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refraction  (r-frkshn) 1. The bending of a wave, such as a light or sound wave, as it passes from one medium to another medium of different density. The change in the angle of propagation depends on the difference between the index of refraction of the original medium and the medium entered by the wave, as well as on the frequency of the wave. Compare reflection. See also lenswave 2. The apparent change in position of a celestial body caused by the bending of light as it enters the Earth's atmosphere. Usage The terms refraction and reflection describe two ways that waves, as of sound or light, change course upon encountering a boundary between two media. The media might consist of two different substances, such as glass and air, or a single substance in different states in different regions, such as air at different temperatures or densities in different layers. Reflection occurs, as in a mirror, when a wave encounters the boundary but does not pass into the second medium, instead immediately changing course and returning to the original medium, typically reflecting from the surface at the same angle at which it contacted it. Refraction occurs, as in a lens, when a wave passes from one medium into the second, deviating from the straight path it otherwise would have taken. The amount of deviation or "bending" depends on the indexes of refraction of each medium, determined by the relative speed of the wave in the two media. Waves entering a medium with a higher index of refraction are slowed, leaving the boundary and entering the second medium at a greater angle than the incident wave. Waves entering a medium with a lower index are accelerated and leave the boundary and enter the second medium at a lesser angle. Incident light waves tend to be fully reflected from a boundary met at a shallow angle; at a certain critical angle and at greater angles, some of the light is also refracted; looking at the surface of water from a boat, for instance, one can see down into the water only out to where the sight line reaches the critical angle with the surface. Light passing through a prism is mostly refracted, or bent, both when it enters the prism and again when it leaves the prism. Since the index of refraction in most substances depends on the frequency of the wave, light of different colors is refracted by different amountshence the colorful rainbow effect of prisms. The boundary between media does not have to be abrupt for reflection or refraction to occur. On a hot day, the air directly over the surface of an asphalt road is warmer than the air higher up. Light travels more quickly in the lower region, so light coming down from the sky (from not too steep an angle) is refracted back up again, giving a "blue puddle" appearance to the asphalta mirage.

refraction Light waves bend as they pass from one substance to another. This pencil appears to be bent at various angles as the light passes through air only; through air and glass; through water, air, and glass; and through water and glass.

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The process by which the direction of a wave is changed when moving into shallow water at an angle to the bathymetric contours. The crest of the wave advancing in shallower water moves more slowly than the crest still advancing in deeper water, causing the wave crest to bend toward alignment with the underwater contours.

Thesaurus

Noun	1.	refraction - the change in direction of a propagating wave (light or sound) when passing from one medium to another physical phenomenon - a natural phenomenon involving the physical properties of matter and energy birefringence, double refraction - splitting a ray into two parallel rays polarized perpendicularly
	2.	refraction - the amount by which a propagating wave is bent deflexion, deflection bending, bend - movement that causes the formation of a curve