Refraction of light at the interface between two media of different refractive indices, with n₂ > n₁. Since the phase velocity is lower in the second medium (v₂ < v₁), the angle of refraction θ₂ is less than the angle of incidence θ₁; that is, the ray in the higher-index medium is closer to the normal.

The straw seems to be broken, due to refraction of light as it emerges into the air.

Refraction is the change in direction of a wave due to a change in its speed. This is most commonly seen when a wave passes from one medium to another. Refraction of light is the most commonly seen example, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth. Refraction is described by Snell's law, which states that the angle of incidence is related to the angle of refraction by In metallurgy, refraction is a property of metals that indicates their ability to withstand heat. ... Image File history File links Snells_law. ... Image File history File links Snells_law. ... Image File history File linksMetadata Download high resolution version (614x698, 67 KB) Summary A photo showing refraction of light rays: a soda straw sticking out of a glass of water. ... Image File history File linksMetadata Download high resolution version (614x698, 67 KB) Summary A photo showing refraction of light rays: a soda straw sticking out of a glass of water. ... Surface waves in water This article is about waves in the most general scientific sense. ... This article does not cite any references or sources. ... A medium is material through which waves propagate; electromagnetic waves in optics. ... For other uses, see Light (disambiguation). ... This article is about compression waves. ... Refraction of light at the interface between two media of different refractive indices, with n2 > n1. ...

or

where v₁ and v₂ are the wave velocities through the respective media.

Explanation

In optics, refraction occurs when light waves travel from a medium with a given refractive index to a medium with another. At the boundary between the media, the wave's phase velocity is altered, it changes direction, and its wavelength increases or decreases but its frequency remains constant. For example, a light ray will refract as it enters and leaves glass; understanding of this concept led to the invention of lenses and the refracting telescope. For the book by Sir Isaac Newton, see Opticks. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye, or in a more general sense, any electromagnetic radiation in the range from infrared to ultraviolet. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... The phase velocity of a wave is the rate at which the phase of the wave propagates in space. ... For other uses, see Wavelength (disambiguation). ... For other uses, see Frequency (disambiguation). ... In optics, a ray is an idealized narrow beam of light. ... This article is about the material. ... For the musical form, see Invention (music). ... This article is about the optical device. ... Image of a refracting telescope from the Cincinnati Observatory in 1848 A refracting or refractor telescope is a dioptric telescope that uses a lens as its objective to form an image. ...

Refraction of light waves in water. The dark rectangle represents the actual position of a pencil sitting in a bowl of water. The light rectangle represents the apparent position of the pencil. Notice that the end (X) looks like it is at (Y), a position that is considerably shallower than (X).

Photograph of refraction of waves in a ripple tank

Refraction can be seen when looking into a bowl of water. Air has a refractive index of about 1.0003, and water has a refractive index of about 1.33. If a person looks at a straight object, such as a pencil or straw, which is placed at a slant, partially in the water, the object appears to bend at the water's surface. This is due to the bending of light rays as they move from the water to the air. Once the rays reach the eye, the eye traces them back as straight lines (lines of sight). The lines of sight (shown as dashed lines) intersect at a higher position than where the actual rays originated. This causes the pencil to appear higher and the water to appear shallower than it really is. The depth that the water appears to be when viewed from above is known as the apparent depth. This is an important consideration for spearfishing from the surface because it will make the target fish appear to be in a different place, and the fisher must aim lower to catch the fish. Diagram of the refraction and apperntly depth compression of a pencil sticking out of a bowl of water. ... Image File history File linksMetadata Download high-resolution version (1544x1024, 150 KB)Photographer: Armedblowfish License: BSD Date taken: 2006, sometime during or around May Camera: Film, Nikon N65 Lens: Nikon 28-80 mm f/3. ... Image File history File linksMetadata Download high-resolution version (1544x1024, 150 KB)Photographer: Armedblowfish License: BSD Date taken: 2006, sometime during or around May Camera: Film, Nikon N65 Lens: Nikon 28-80 mm f/3. ... Wikibooks has more about this subject: School science how-to In physics and engineering, a ripple tank is a shallow glass tank of water used in schools and colleges to demonstrate the basic properties of waves. ... // Dutch fishermen using tridents in the 17th century Night spear fishing, Amazon basin, Peru. ...

Diagram of refraction of water waves

The diagram on the right shows an example of refraction in water waves. Ripples travel from the left and pass over a shallower region inclined at an angle to the wavefront. The waves travel more slowly in the shallower water, so the wavelength decreases and the wave bends at the boundary. The dotted line represents the normal to the boundary. The dashed line represents the original direction of the waves. The phenomenon explains why waves on a shoreline never hit the shoreline at an angle. Whichever direction the waves travel in deep water, they always refract towards the normal as they enter the shallower water near the beach. Diagram of waves refracting drawn by Theresa Knott File links The following pages link to this file: Refraction Ripple tank User:Theresa knott/image gallery Categories: GFDL images ... Diagram of waves refracting drawn by Theresa Knott File links The following pages link to this file: Refraction Ripple tank User:Theresa knott/image gallery Categories: GFDL images ... Waves breaking on rocks at La Jolla Waves Ocean surface waves are surface waves which occur at the surface of an ocean. ... A surface normal, or just normal to a flat surface is a three-dimensional vector which is perpendicular to that surface. ...

Refraction is also responsible for rainbows and for the splitting of white light into a rainbow-spectrum as it passes through a glass prism. Glass has a higher refractive index than air and the different frequencies of light travel at different speeds (dispersion), causing them to be refracted at different angles, so that you can see them. The different frequencies correspond to different colors observed. For other uses, see Rainbow (disambiguation). ... Diagram of a triangular prism, dispersing light Lamps as seen through a prism. ... Dispersion of a light beam in a prism. ...

While refraction allows for beautiful phenomena such as rainbows it may also produce peculiar optical phenomena, such as mirages and Fata Morgana. These are caused by the change of the refractive index of air with temperature. An optical phenomenon is any observable event which results from the interaction of light and matter. ... This article is about the optical phenomenon. ... A fata Morgana, named after Morgan le Fay, the faery shapeshifting half-sister of King Arthur, is a mirage, an optical phenomenon which results from a temperature inversion. ...

Refraction in a Perspex (acrylic) block.

Snell's law is used to calculate the degree to which light is refracted when traveling from one medium to another. refraction in a perspex block Taken by fir0002 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... refraction in a perspex block Taken by fir0002 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Perspex redirects here. ... Refraction of light at the interface between two media of different refractive indices, with n2 > n1. ...

Recently some metamaterials have been created which have a negative refractive index. With metamaterials, we can also obtain the total refraction phenomena when the wave impedances of the two media are matched. There is no reflected wave. A metamaterial (or meta material) is a material that gains its properties from its structure rather than directly from its composition. ... In electromagnetism (covering areas like optics and photonics), a meta material (or metamaterial) is an object that gains its (electromagnetic) material properties from its structure rather than inheriting them directly from the materials it is composed of. ... Total refraction is when an incident wave on an interface between two media with opposite refractive index signs is completely transmitted. ...

Also, since refraction can make objects appear closer than they are, it is responsible for allowing water to magnify objects. First, as light is entering a drop of water, it slows down. If the water's surface is not flat, then the light will be bent into a new path. This round shape will bend the light outwards and as it spreads out, the image you see gets larger.

A useful analogy in explaining the refraction of light would be to imagine a marching band as they march from pavement (a fast medium) into mud (a slower medium) The marchers on the side that runs into the mud first will slow down first. This causes the whole band to pivot slightly toward the normal (make a smaller angle from the normal).

Ophthalmology

In medicine, particularly ophthalmology and optometry, refraction (also known as refractometry) is a clinical test in which a phoropter is used to determine the eye's refractive error and the best corrective lenses to be prescribed. A series of test lenses in graded optical powers or focal lengths are presented to determine which provide the sharpest, clearest vision.^[1] For the chemical substances known as medicines, see medication. ... This article is about the branch of medicine. ... Optometry (Greek: optos meaning seen or visible and metria meaning measurement) is a health care profession concerned with eyes and related structures, vision, visual system and vision information processing in humans. ... A refractor in use The name and shape of the PHOROPTOR® is a registered trademark of Reichert, Inc. ... Refraction error, also known as refractive error, is an error in the focusing of light by the eye and a frequent reason for reduced visual acuity. ... A bifocal corrective eyeglasses lens A corrective lens is a lens worn on or before the eye, used to treat myopia, hyperopia, astigmatism, and presbyopia. ... Optical power or dioptric power or refractive power is the degree to which a lens or mirror converges or diverges light. ... This article is about focal length related to lenses and systems of lenses. ...

Acoustics

In underwater acoustics, refraction is the bending or curving of a sound ray that results when the ray passes through a sound speed gradient from a region of one sound speed to a region of a different speed. The amount of ray bending is dependent upon the amount of difference between sound speeds, that is, the variation in temperature, salinity, and pressure of the water.^[2] Similar acoustics effects are also found in the Earth's atmosphere. The phenomenon of refraction of sound in the atmosphere has been known for centuries;^[3] however, beginning in the early 1970s, widespread analysis of this effect came into vogue through the designing of urban highways and noise barriers to address the meteorological effects of bending of sound rays in the lower atmosphere.^[4] Underwater acoustics is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water and its boundaries. ... In acoustics, the sound speed gradient is the rate of change of the speed of sound with depth in the ocean,[1] or height in the Earths atmosphere. ... Acoustics is the branch of physics concerned with the study of sound (mechanical waves in gases, liquids, and solids). ... Air redirects here. ... This article or section does not cite any references or sources. ... The sound tube in Melbourne, Australia, designed to reduce roadway noise without detracting from the areas aesthetics. ... Meteorology is the scientific study of the atmosphere that focuses on weather processes and forecasting. ...

See also

• List of indices of refraction
• Reflection
• Willebrord Snellius
• Snell's Law
• Total internal reflection
• Total refraction
• Huygens-Fresnel principle
• Light
• Birefringence (Double refraction)

Many materials have a well-characterized refractive index, but these indices depend strongly upon the wavelength of light. ... The reflection of a bridge in Indianapolis, Indianas Central Canal. ... Willebrord Snellius[1] (born Willebrord Snel van Royen[2]) (1580–October 30, 1626, Leiden) was a Dutch astronomer and mathematician, most famous for the law of refraction now known as Snells law. ... Refraction of light at the interface between two media of different refractive indices, with n2 > n1. ... The larger the angle to the normal, the smaller is the fraction of light transmitted, until the angle when total internal reflection occurs. ... Total refraction is when an incident wave on an interface between two media with opposite refractive index signs is completely transmitted. ... Wave Refraction in the manner of Huygens. ... For other uses, see Light (disambiguation). ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on...

References

1. ^ Eye Glossary. Retrieved on 2006-05-23.
2. ^ (August 2006) Navy Supplement to the DOD Dictionary of Military and Associated Terms. Department Of The Navy. NTRP 1-02. 
3. ^ Mary Somerville, On the Connexion of the Physical Sciences, J. Murray Publishers, (originally by Harvard University), 499 pages (1840)
4. ^ [1] C. Michael Hogan, Analysis of highway noise, Journal Water, Air, & Soil Pollution, Publisher Springer Netherlands, ISSN 0049-6979, Volume 2, Number 3, Pages 387-392, September, 1973

• David W. Ward and Keith A. Nelson: On the Physical Origins of the Negative Index of Refraction, New Journal of Physics, 7, 213 (2005).

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 143rd day of the year (144th in leap years) in the Gregorian calendar. ... USN redirects here. ...

External links

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Refraction

• Java explanatory animation
• Java illustration of refraction
• Java simulation of refraction through a prism