Refraction | Define Refraction at Dictionary.com refraction noun 1. Physics. the change of direction of a ray of light, sound, heat, or the like, in passing obliquely from one medium into another in which its wave velocity is different. 2. Ophthalmology. the ability of the eye to refract light that enters it so as to form an image on the retina. the determining of the refractive condition of the eye. 3. Astronomy. Also called astronomical refraction. the amount, in angular measure, by which the altitude of a celestial body is increased by the refraction of its light in the earth's atmosphere, being zero at the zenith and a maximum at the horizon. the observed altered location, as seen from the earth, of another planet or the like due to diffraction by the atmosphere. Origin of refraction 1570-80; < Late Latin refrāctiōn- (stem of refrāctiō). See refract , -ion Related forms Examples from the Web for refraction Expand Aether and Gravitation William George Hooper The deception is due to refraction, and the material and shape of the bottle furnish a sufficient explanation. General Science Bertha M.

Clark The formula for refraction which Ptolemy helped to shape, is geometrical in form. Scenes and Characters Charlotte M. Yonge The changing arising from refraction and reflection is wonderful. Olla Podrida Frederick Marryat (AKA Captain Marryat) The refraction of light as it passes through an intervening cloud, or a stratum of moist and cold air. British Dictionary definitions for refraction Expand noun 1. (physics) the change in direction of a propagating 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 3. the ability of the eye to refract light 4. the determination of the refractive condition of the eye 5. (astronomy) the apparent elevation in position of a celestial body resulting from the refraction of light by the earth's atmosphere Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd.

1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Word Origin and History for refraction Expand n. 1570s, from Late Latin refractionem (nominative refractio) "a breaking up," noun of action from past participle stem of Latin refringere "to break up," from re- "back" (see re- ) + comb. form of frangere "to break" (see fraction ). Online Etymology Dictionary, © 2010 Douglas Harper refraction re·frac·tion (rĭ-frāk'shən) n. The turning or bending of any wave, such as a light or sound wave, when it passes from one medium into another of different density. The ability of the eye to bend light so that an image is focused on the retina. Determination of the refractive characteristics of the eye and often the correction of refractive defects with lenses. Also called refringence.

re·frac'tion·al or re·frac'tive adj. re·frac'tive·ness or re'frac·tiv'i·ty (rē'frāk-tĭv'ĭ-tē) n. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company. refraction (rĭ-frāk'shən) 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 lens , wave. The apparent change in position of a celestial body caused by the bending of light as it enters the Earth's atmosphere. Our Living Language : 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 amounts—hence 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 asphalt—a mirage. The American Heritage® Science Dictionary Copyright © 2002. Published by Houghton Mifflin. All rights reserved.

Reflection, Refraction, and Diffraction Waves - Lesson 3 - Behavior of Waves Reflection, Refraction, and Diffraction The Doppler Effect Previously in Lesson 3 , the behavior of waves traveling along a rope from a more dense medium to a less dense medium (and vice versa) was discussed. The wave doesn't just stop when it reaches the end of the medium. Rather, a wave will undergo certain behaviors when it encounters the end of the medium. Specifically, there will be some reflection off the boundary and some transmission into the new medium. But what if the wave is traveling in a two-dimensional medium such as a water wave traveling through ocean water? Or what if the wave is traveling in a three-dimensional medium such as a sound wave or a light wave traveling through air? What types of behaviors can be expected of such two- and three-dimensional waves? The study of waves in two dimensions is often done using a ripple tank. A ripple tank is a large glass-bottomed tank of water that is used to study the behavior of water waves. A light typically shines upon the water from above and illuminates a white sheet of paper placed directly below the tank. A portion of light is absorbed by the water as it passes through the tank.

A crest of water will absorb more light than a trough. So the bright spots represent wave troughs and the dark spots represent wave crests. As the water waves move through the ripple tank, the dark and bright spots move as well. As the waves encounter obstacles in their path, their behavior can be observed by watching the movement of the dark and bright spots on the sheet of paper. Ripple tank demonstrations are commonly done in a Physics class in order to discuss the principles underlying the reflection, refraction, and diffraction of waves. Reflection of Waves If a linear object attached to an oscillator bobs back and forth within the water, it becomes a source of straight waves. These straight waves have alternating crests and troughs. As viewed on the sheet of paper below the tank, the crests are the dark lines stretching across the paper and the troughs are the bright lines. These waves will travel through the water until they encounter an obstacle - such as the wall of the tank or an object placed within the water. The diagram at the right depicts a series of straight waves approaching a long barrier extending at an angle across the tank of water. The direction that these wavefronts (straight-line crests) are traveling through the water is represented by the blue arrow.

The blue arrow is called a ray and is drawn perpendicular to the wavefronts. Upon reaching the barrier placed within the water, these waves bounce off the water and head in a different direction. The diagram below shows the reflected wavefronts and the reflected ray. Regardless of the angle at which the wavefronts approach the barrier, one general law of reflection holds true: the waves will always reflect in such a way that the angle at which they approach the barrier equals the angle at which they reflect off the barrier. This is known as the law of reflection. This law will be discussed in more detail in Unit 13 of The Physics Classroom . The discussion above pertains to the reflection of waves off of straight surfaces. But what if the surface is curved, perhaps in the shape of a parabola? What generalizations can be made for the reflection of water waves off parabolic surfaces? Suppose that a rubber tube having the shape of a parabola is placed within the water. The diagram at the right depicts such a parabolic barrier in the ripple tank. Several wavefronts are approaching the barrier; the ray is drawn for these wavefronts. Upon reflection off the parabolic barrier, the water waves will change direction and head towards a point.

This is depicted in the diagram below. It is as though all the energy being carried by the water waves is converged at a single point - the point is known as the focal point. After passing through the focal point, the waves spread out through the water. Reflection of waves off of curved surfaces will be discussed in more detail in Unit 13 of The Physics Classroom . Refraction of Waves Reflection involves a change in direction of waves when they bounce off a barrier. Refraction of waves involves a change in the direction of waves as they pass from one medium to another. Refraction, or the bending of the path of the waves, is accompanied by a change in speed and wavelength of the waves. In Lesson 2 , it was mentioned that the speed of a wave is dependent upon the properties of the medium through which the waves travel. So if the medium (and its properties) is changed, the speed of the waves is changed. The most significant property of water that would affect the speed of waves traveling on its surface is the depth of the water. Water waves travel fastest when the medium is the deepest. Thus, if water waves are passing from deep water into shallow water, they will slow down.

And as mentioned in the previous section of Lesson 3 , this decrease in speed will also be accompanied by a decrease in wavelength. So as water waves are transmitted from deep water into shallow water, the speed decreases, the wavelength decreases, and the direction changes. This boundary behavior of water waves can be observed in a ripple tank if the tank is partitioned into a deep and a shallow section. If a pane of glass is placed in the bottom of the tank, one part of the tank will be deep and the other part of the tank will be shallow. Waves traveling from the deep end to the shallow end can be seen to refract (i.e., bend), decrease wavelength (the wavefronts get closer together), and slow down (they take a longer time to travel the same distance). When traveling from deep water to shallow water, the waves are seen to bend in such a manner that they seem to be traveling more perpendicular to the surface. If traveling from shallow water to deep water, the waves bend in the opposite direction. The refraction of light waves will be discussed in more detail in a later unit of The Physics Classroom .

Diffraction of Waves Reflection involves a change in direction of waves when they bounce off a barrier; refraction of waves involves a change in the direction of waves as they pass from one medium to another; and diffraction involves a change in direction of waves as they pass through an opening or around a barrier in their path. Water waves have the ability to travel around corners, around obstacles and through openings. This ability is most obvious for water waves with longer wavelengths. Diffraction can be demonstrated by placing small barriers and obstacles in a ripple tank and observing the path of the water waves as they encounter the obstacles. The waves are seen to pass around the barrier into the regions behind it; subsequently the water behind the barrier is disturbed. The amount of diffraction (the sharpness of the bending) increases with increasing wavelength and decreases with decreasing wavelength. In fact, when the wavelength of the waves is smaller than the obstacle, no noticeable diffraction occurs. Diffraction of water waves is observed in a harbor as waves bend around small boats and are found to disturb the water behind them. The same waves however are unable to diffract around larger boats since their wavelength is smaller than the boat.

Diffraction of sound waves is commonly observed; we notice sound diffracting around corners, allowing us to hear others who are speaking to us from adjacent rooms. Many forest-dwelling birds take advantage of the diffractive ability of long-wavelength sound waves. Owls for instance are able to communicate across long distances due to the fact that their long-wavelength hoots are able to diffract around forest trees and carry farther than the short-wavelength tweets of songbirds. Diffraction is observed of light waves but only when the waves encounter obstacles with extremely small wavelengths (such as particles suspended in our atmosphere). Diffraction of sound waves and of light waves will be discussed in a later unit of The Physics Classroom Tutorial . Reflection, refraction and diffraction are all boundary behaviors of waves associated with the bending of the path of a wave. The bending of the path is an observable behavior when the medium is a two- or three-dimensional medium. Reflection occurs when there is a bouncing off of a barrier. Reflection of waves off straight barriers follows the law of reflection. Reflection of waves off parabolic barriers results in the convergence of the waves at a focal point. Refraction is the change in direction of waves that occurs when waves travel from one medium to another.

Refraction is always accompanied by a wavelength and speed change. Diffraction is the bending of waves around obstacles and openings. The amount of diffraction increases with increasing wavelength. Light refraction - definition of Light refraction by The Free Dictionary Light refraction - definition of Light refraction by The Free Dictionary Related to Light refraction: Light reflection refraction (rĭ-frăk′shən) n. 1. The deflection of a wave, such as a light or sound wave, when it passes obliquely from one medium into another having a different index of refraction. 2. Astronomy The apparent change in position of a celestial object caused by the bending of light rays as they enter 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 this ability in an eye. re·frac′tion·al, re·frac′tive adj. re·frac′tive·ly adv. re·frac′tive·ness, re′frac·tiv′i·ty (rē′frăk-tĭv′ĭ-tē) n.

refraction (rɪˈfrækʃən) n 1. (General Physics) physics the change in direction of a propagating wave, such as light or sound, in passing from one medium to another in which it has a different velocity 2. (General Physics) the amount by which a wave is refracted 3. (Physiology) the ability of the eye to refract light 4. (Medicine) the determination of the refractive condition of the eye 5. (Astronomy) astronomy the apparent elevation in position of a celestial body resulting from the refraction of light by the earth's atmosphere re•frac•tion (rɪˈfræk ʃən) n. 1. the change of direction of a ray of light, sound, heat, or the like, in passing obliquely from one medium into another in which its wave velocity is different. 2. a. the ability of the eye to refract light that enters it so as to form an image on the retina. b. the determining of the refractive condition of the eye. 3. the amount, in angular measure, by which the altitude of a celestial body is increased by the refraction of its light in the earth's atmosphere.

[1570–80; < Late Latin refrāctiō, calque of Greek anáklasis. See refract , -tion ] 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. re·frac·tion (rĭ-frăk′shən) 1. The bending or turning of a wave, such as a light or sound wave, when it passes from one medium to another medium of different density. See more at wave . Compare reflection . 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 words refraction and reflection describe two different ways that a light wave, sound wave, or other wave can move when it encounters a boundary between two media. The media can be two different substances, such as glass and air, or they can be regions of a single substance that are in different states, such as regions of air that are at different temperatures. Reflection occurs when a wave hits the boundary and returns immediately to its original medium.

Refraction occurs when a wave passes from one medium to another and is bent; that is, the wave deviates from the straight-line path it would have otherwise followed. For example, light passing through a prism is bent when it enters the prism and again when it leaves the prism. The light is therefore refracted. Light striking a mirror bounces off the silver backing without entering it. The light is therefore reflected. The boundary between the media does not have to be abrupt for reflection or refraction to occur. On a hot day, the air over the surface of an asphalt road is warmer than the air above it. Because light travels at different speeds in these two regions, we see an image that shimmers because its light waves are refracted. refraction 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. refraction The bending of a sound wave or ray of light as it passes from one medium to another. ThesaurusAntonymsRelated WordsSynonymsLegend: What does refraction mean?

This page provides all possible meanings and translations of the word refraction Princeton's WordNet(0.00 / 0 votes)Rate this definition: refraction(noun) the change in direction of a propagating wave (light or sound) when passing from one medium to another deflection, deflexion, refraction(noun) the amount by which a propagating wave is bent Wiktionary(5.00 / 1 vote)Rate this definition: refraction(Noun) 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. refraction(Noun) The degree to which a metal or compound can withstand heat Webster Dictionary(0.00 / 0 votes)Rate this definition: Refraction(noun) Freebase(0.00 / 0 votes)Rate this definition: Refraction Refraction is the change in direction of a wave due to a change in its optical medium. Refraction is essentially a surface phenomenon. The phenomenon is mainly in governance to the law of conservation of energy and momentum. Due to change of medium, the phase velocity of the wave is changed but its frequency remains constant.

This is most commonly observed when a wave passes from one medium to another at any angle other than 90° or 0°. Refraction of light is the most commonly observed phenomenon, 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 for a given pair of media and a wave with a single frequency, the ratio of the sines of the angle of incidence θ1 and angle of refraction θ2 is equivalent to the ratio of phase velocities in the two media, or equivalently, to the opposite ratio of the indices of refraction: In general, the incident wave is partially refracted and partially reflected; the details of this behavior are described by the Fresnel equations. The Nuttall Encyclopedia(0.00 / 0 votes)Rate this definition: Refraction . Light travels in straight lines; but when a ray travelling through one medium passes obliquely into another of either greater or less density it is bent at the point of incidence. This bending or breaking is called refraction.

The apparent bend in a stick set sloping in a sheet of water is due to this phenomenon, as are also many mirages and other optical illusions. Dictionary of Military and Associated Terms(0.00 / 0 votes)Rate this definition: refraction 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. The numerical value of refraction in Chaldean Numerology is: 2 Pythagorean Numerology Refraction, Refraction of Light | Physics@TutorVista.com The deviation in the path of light when it passes from one medium to another medium of different density is called Refraction. Wave Refraction Back to Top We see a boat on a sea moving up and down along with the waves and at the same time maintaining a horizontal movement. Imagine a particle makes this kind of motion without water. We will be invariably reminded of the motion of a boat along with the waves in the sea.

For the same reason, a horizontal motion with an up and down oscillation is called a wave motion. Wave refraction is a phenomenon that takes when a wave passes through one medium to another medium. Refraction of Light Back to Top All electromagnetic transmissions including light are wave motions only. The wave length and the amplitudes are infinitely small, we indicate such wave motions as straight lines in our study. Since, light rays also indicate a wave motion, concept involved in refraction of light and in wave refraction are exactly the same. Back to Top We define a ratio of velocity of a light ray in vacuum to the velocity of the light ray in a given medium as a constant ‘n’. This constant ‘n’ is called as the ‘refractive index’ of the medium or the ‘index of refraction’ of the medium. $n$ = $\frac{c}{v}$ This concept will be of great use later when we discuss the law of refraction. That is, the rule which is followed by the refraction of a wave. → Read More Law of Refraction Back to Top As mentioned earlier, a light ray travels in different velocities in different mediums. In that process, the direction of ray changes when it enters the second medium.

As per Snell’s law, the sin of the angle made by the ray with the normal to the surface of interface between the mediums is directly proportional to the velocity in that medium. This law can be mathematically explained with the following diagram. We know that the phenomenon of refraction is taking place as the speed of light changes when it is traveling from one optical medium to another. Thus, we can define refractive index in terms of the speed of light in the two media.

As per Snell’s law, $\frac{\sin i}{\sin r}$ = $\frac{v_{I}}{v_{R}}$ Where, $v_{I}$ - The velocity of the incident light $v_{R}$ - The velocity of the refracted light i - The angle of incidence r - The angle of refraction Now, bringing the concept of refractive index of the media by the relation $v$ = $\frac{c}{n}$, $\frac{\sin i}{\sin r}$ = $\frac{n_{2}}{n_{1}}$ That is, the ratio of sine of the angle of incidence and the sine of the angle of refraction of a ray when it crosses a medium is the ratio of the refractive index of the second medium to that of the first medium. This is the mathematical form of law of refraction and known as Snell’s Law of Refraction after the scientist Willebrod Snellius who first formulated it.

The refractive index of glass with respect to air is given by the relation, $Air n_{glass}$ = $\frac {Speed\ of\ light\ in\ air}{Speed\ of\ light\ in\ glass}$ = $\frac {c}{v}$ In general, if a ray of light is passing from medium 1 to medium 2, then $1n_{2}$ = $\frac {Speed\ of\ light\ in\ medium\ 1}{Speed\ of\ light\ in\ medium\ 2}$ If the medium 1 is air or vacuum, the refractive index of medium 2 is referred to as the Absolute Refractive Index. The Refractive Index of a medium depends on the following factors: The nature of the medium The color or wavelength of the incident light Negative Refraction Back to Top Look at the above diagram. A ray IO crosses from medium 1 (Air) to medium 2 (Glass) at point O. Normally the ray undergoes refraction at O. It bends away from the normal as OR1 if the medium 2 is lighter than 1 or bends towards the normal as OR if the medium 2 is heavier than 1.

In rare cases, if the medium has a negative permittivity and negative permeability, the ray gets bent as ORn, on the opposite side of normal. In a way it looks like as if the ray is reflected back, but to the second medium. This type of refraction is called Negative Refraction. Water Refraction Back to Top Water refraction is a common phenomenon experienced by us often in real life. Water refraction is a matter of common experience that a spoon placed in a glass of water looks bent at the surface of water when viewed obliquely. This observation suggests that light changes its path as it passes from one medium to another. This change in the path of light is due to the fact that the velocity of light varies as it travels from one medium to another. The deviation in the path of light when it passes from one medium to another medium of different density is due to refraction. An example is illustrated below. The fish AB is actually at the bottom of the pond. The light rays AC and BD crosses the medium of water to air at C and D. From there they emerge out as rays CE and DF after refraction due to change in medium.

But to a person at EF, the eye manipulates as if the rays are coming straight from A’ and B’ and this A’B’ appears to be a virtual position of the fish at a lower depth compared to the actual depth. Refraction of Sound Back to Top Sound transmission is also a wave motion, sound waves also undergo refraction. The speed of sound depends on the temperature of the medium and hence we can explain the effect of refraction of sound in the same medium but at different temperatures. It can be noticed that in night hours we are able to hear sound from a greater distance compared to day time. This can be explained if the concept of refraction of sound is understood. Sound also travels as a wave motion although the type of wave is different. The velocity of sound also varies with the air temperature. In day time, the temperature of air increases as altitude increases. On the other hand, at night/early morning hours the temperature of air decreases with the increase in altitude. Thus the air layers of different sections act as different mediums for the sound waves and undergoes refraction at each interface. In day time, the direction of wave motion is upwards and with a shorter wave length. In case of night hours it is just the reverse.

Therefore, the sound waves have a better horizontal reach in night hours. Seismic Refraction Back to Top Energy is transferred in forms of wave motions, called seismic waves, crossing different layers of earth. This can be felt when there is an earth quake or when an eruption from a volcano. Also, here the velocity of the wave varies from layer to layer. The velocities at layers close to the surface of earth are higher compared to the velocity of waves at deeper layers. The change in velocities of the seismic waves between the layers amounts to a refraction, called seismic refraction. Geological scientists have found that a seismic refraction also follows Snell’s law. Double Refraction Back to Top A Double Refraction is a dual refraction that happens at a single interface. Some mediums called anisotropic mediums can polarize a ray into two orthogonal rays as shown below. In the above diagram the rectangle represents the face of an anisotropic medium. The optical axis of the crystal is the line ‘x’ shown in blue. If a ray enters the face in the direction of line ‘x’, then the ray passes as it is.

However if a ray R enters in any other direction, say at A, as shown in the diagram, then it is split into a set of two rays AO and AE in orthogonal directions. The ray AO is called as ordinary ray and emerges out following Snell’s law. The ray AE is called extraordinary ray and emerges without following Snell’s law. Thus an observer on the right is able to see two images for the same object. This is called double refraction. What Causes Refraction? Back to Top A wave travels at different velocities in different mediums. But the frequency of the motion is not altered. Since the phase velocity is frequency times the wave length, a change in phase velocity means a change in wave length. The change in velocity also results change in direction of the wave propagation which we defined as the wave refraction or refraction of a light ray. Reflection and Refraction Back to Top When a light ray passes from one medium to another medium, the light ray may be totally absorbed by the boundary if it is an opaque surface. In such a case, no light is seen on the other medium. In some cases the light ray may be sent back, following a rule, to the same medium if the boundary has the ability to do so.

This phenomenon of light ray ‘being sent back’ is called ‘Reflection’ of light ray and the ‘ability’ of the boundary is called as ‘reflective property’ of the medium. However, in most cases, the boundary is transparent and the light ray is able to enter the second medium. However, the path of the light ray will no longer be the same. Depending on many factors, it may bend towards the normal to the surface, away from the normal to the surface or, in exceptional cases, the ray be even be reflected back. In any case the phenomenon of any of such things happening is called the ‘Refraction’ of the light ray. The refraction of light ray also follows a certain rule. Back to Top The law relating to reflection and refraction is called Snell’s law which is one of the important concepts in optics. When a light hits a surface, it is totally absorbed if the surface is opaque. But if the surface is reflective, the light ray is ‘reflected’ or if the surface is transparent and if the medium of the other side is different the light tray undergoes ‘refraction’.

The Cause of Refraction Refraction and the Ray Model of Light - Lesson 1 - Refraction at a Boundary The Cause of Refraction If I Were an Archer Fish We have learned that refraction occurs as light passes across the boundary between two media. Refraction is merely one of several possible boundary behaviors by which a light wave could behave when it encounters a new medium or an obstacle in its path. The transmission of light across a boundary between two media is accompanied by a change in both the speed and wavelength of the wave. The light wave not only changes directions at the boundary, it also speeds up or slows down and transforms into a wave with a larger or a shorter wavelength. The only time that a wave can be transmitted across a boundary, change its speed, and still not refract is when the light wave approaches the boundary in a direction that is perpendicular to it. As long as the light wave changes speed and approaches the boundary at an angle, refraction is observed. The Marching Soldiers But why does light refract? What is the cause of such behavior? And why is there this one exception to the refraction of light? An analogy of marching soldiers is often used to address this question.

In fact, it is not uncommon that the analogy be illustrated in a Physics class with a student demonstration. A group of students forms a straight line (shoulder to shoulder) and connect themselves to their nearest neighbor using meter sticks. A strip of masking tape divides the room into two media. In one of the media (on one side of the tape), students walk at a normal pace. In the other media (or on the other side of the tape), students walk very slowly using baby steps. The group of students walk forward together in a straight line towards the diagonal strip of masking tape. The students maintain the line as they approach the masking tape. When an individual student reaches the tape, that student abruptly changes the pace of her/his walk. The group of students continues walking until all students in the line have entered into the second medium. The diagram below represents the line of students approaching the boundary (the masking tape) between the two media. On the diagram, an arrow is used to show the general direction of travel for the group of students in both media. Observe that the direction of the students changes at the "boundary." The fundamental feature of the students' motion that leads to this change in direction is the change in speed.

Upon reaching the masking tape, each individual student abruptly changes speed. Because the students approach the masking tape at an angle, each individual student reaches the tape at a different time. The student who reaches the tape first, slows down while the rest of the line of students marches ahead. This occurs for every student in the line of students. Once a student reaches the boundary, that student slows down while his/her nearest neighbor marches ahead at the original pace. The result is that the direction that the line of students is heading is altered at the boundary. The change in speed of the line of students causes a change in direction. Conditions of Refraction Will this refractive behavior always occur? No! There are two conditions that are required in order to observe the change in direction of the path of the students: The students must change speed when crossing the boundary. The students must approach the boundary at an angle; refraction will not occur when they approach the boundary head-on (i.e., heading perpendicular to it). These are both reasonable enough conditions if you consider the previous paragraph. If the students do not change speed, then there is no cause factor. Recall that it was the change in speed of the students that caused the change in direction. The second condition is also reasonable.

If the students approach the masking tape in a direction that is perpendicular to it, then each student will reach the tape at the exact same time. Recall that the line of student changed their direction because they had reached the masking tape at different times. The first student reached the tape, slowed down, and observed the rest of the students marching ahead at the original speed. The change in direction of the line of students only occurs at the boundary when the students change speed and approach at an angle. The Marching Soldiers analogy provides an excellent analogy to understanding the cause of light refraction. The line of students approaching the masking tape are analogous to a wavefront of light. The masking tape is analogous to a boundary between two media. The change in speed that occurred for the line of students would also occur for a wave of light. And like the marching students, a light wave will not undergo refraction if it approaches the boundary in a direction that is perpendicular to it. The same two conditions that are necessary for bending the path of the line of students are also necessary for bending the direction of a light ray. Light refracts at a boundary because of a change in speed. There is a distinct cause-effect relationship.

The change in speed is the cause and the change in direction (refraction) is the effect. Refraction | Computer Graphics | Fandom powered by Wikia Share Refraction is the change in direction of a wave due to a change in its velocity . 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. 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 . File:Pencil in a bowl of water.png 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).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, 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. File:Refraction in a ripple tank.png Refraction of waves in a ripple tankThe 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. 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 colours observed. File:Inferior Image.JPG Inferior image formed when light travels from cold air to warm air. The image of the sky appears on the hot ground.While refraction allows for beautiful phenomena such as rainbows it may also produce peculiar optical illusions .

A common illusion is a mirage , which occurs when light rays refract as they pass from cold air to warm air. Although 1.0003 is a commonly accepted value for the refractive index of air, the index varies depending on the density of air. Warm air is less dense than cold air and therefore has a lower refractive index . As light passes from colder air to warmer air it bends away from the normal. The diagram on the right shows a light ray coming from the sky toward the hot ground. The air near the ground is warmer and so the light ray bends in a concave up trajectory. Once the ray reaches the viewer’s eye, the eye traces it as the line of sight, which is the line tangent to the path the ray takes at the point it reaches the eye. The result is an inferior image for the above sky appears on the ground. The viewer may incorrectly interpret this sight as water reflecting the sky. File:Refraction.jpg Refraction in a Perspex ( acrylic ) block.A similar illusion occurs when light travels from warm air to cold air. Light rays traveling in such a path are refracted to produce a superior image in which an object appears above its actual position.

An example of this involves cold air above an iceberg. Light rays traveling from warm air toward this cold surface, follow a concave down trajectory. The line of sight traced by the viewer would point up producing such illusions as flying boats. Snell's law is used to calculate the degree to which light is refracted when traveling from one medium to another. 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. In medicine , particularly ophthalmology and optometry , refraction (also known as refractometry) is a clinical test for the determination of an 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 ] See also: phoropter Also, since refraction makes 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. Refraction of waves - definition of Refraction of waves by The Free Dictionary Refraction of waves - definition of Refraction of waves by The Free Dictionary (rĭ-frăk′shən) n. 1. The deflection of a wave, such as a light or sound wave, when it passes obliquely from one medium into another having a different index of refraction. 2. Astronomy The apparent change in position of a celestial object caused by the bending of light rays as they enter 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 this ability in an eye. re·frac′tion·al, re·frac′tive adj. re·frac′tive·ly adv. re·frac′tive·ness, re′frac·tiv′i·ty (rē′frăk-tĭv′ĭ-tē) n.

refraction (rɪˈfrækʃən) n 1. (General Physics) physics the change in direction of a propagating wave, such as light or sound, in passing from one medium to another in which it has a different velocity 2. (General Physics) the amount by which a wave is refracted 3. (Physiology) the ability of the eye to refract light 4. (Medicine) the determination of the refractive condition of the eye 5. (Astronomy) astronomy the apparent elevation in position of a celestial body resulting from the refraction of light by the earth's atmosphere re•frac•tion (rɪˈfræk ʃən) n. 1. the change of direction of a ray of light, sound, heat, or the like, in passing obliquely from one medium into another in which its wave velocity is different. 2. a. the ability of the eye to refract light that enters it so as to form an image on the retina. b. the determining of the refractive condition of the eye. 3. the amount, in angular measure, by which the altitude of a celestial body is increased by the refraction of its light in the earth's atmosphere.

[1570–80; < Late Latin refrāctiō, calque of Greek anáklasis. See refract , -tion ] 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. re·frac·tion (rĭ-frăk′shən) 1. The bending or turning of a wave, such as a light or sound wave, when it passes from one medium to another medium of different density. See more at wave . Compare reflection . 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 words refraction and reflection describe two different ways that a light wave, sound wave, or other wave can move when it encounters a boundary between two media. The media can be two different substances, such as glass and air, or they can be regions of a single substance that are in different states, such as regions of air that are at different temperatures. Reflection occurs when a wave hits the boundary and returns immediately to its original medium.

Refraction occurs when a wave passes from one medium to another and is bent; that is, the wave deviates from the straight-line path it would have otherwise followed. For example, light passing through a prism is bent when it enters the prism and again when it leaves the prism. The light is therefore refracted. Light striking a mirror bounces off the silver backing without entering it. The light is therefore reflected. The boundary between the media does not have to be abrupt for reflection or refraction to occur. On a hot day, the air over the surface of an asphalt road is warmer than the air above it. Because light travels at different speeds in these two regions, we see an image that shimmers because its light waves are refracted. refraction 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. refraction The bending of a sound wave or ray of light as it passes from one medium to another.

ThesaurusAntonymsRelated WordsSynonymsLegend: Refrection of light | Article about Refrection of light by The Free Dictionary Refrection of light | Article about Refrection of light by The Free Dictionary Related to Refrection of light: Refraction of Light , Dispersion of light refraction, in physics, deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different, as the passage of a light ray from air into glass. Other forms of electromagnetic radiation electromagnetic radiation, energy radiated in the form of a wave as a result of the motion of electric charges. A moving charge gives rise to a magnetic field, and if the motion is changing (accelerated), then the magnetic field varies and in turn produces an electric field. ..... Click the link for more information. , in addition to light waves, can be refracted, as can sound waves. The Nature of Refraction Refraction is commonly explained in terms of the wave theory of light and is based on the fact that light travels with greater velocity in some media than it does in others.

When, for example, a ray of light traveling through air strikes the surface of a piece of glass at an oblique angle, one side of the wave front enters the glass before the other and is retarded (since light travels more slowly in glass than in air), while the other side continues to move at its original speed until it too reaches the glass. As a result, the ray bends inside the glass, i.e., the refracted ray lies in a direction closer to the normal (the perpendicular to the boundary of the media) than does the incident ray. A light ray entering a different medium is called the incident ray; after bending, the ray is called the refracted ray. The speed at which a given transparent medium transmits light waves is related to its optical density (not to be confused with mass or weight density density, ratio of the mass of a substance to its volume, expressed, for example, in units of grams per cubic centimeter or pounds per cubic foot. The density of a pure substance varies little from sample to sample and is often considered a characteristic property of the ..... Click the link for more information. ).

In general, a ray is refracted toward the normal when it passes into a denser medium and away from the normal when it passes into a less dense medium. The Law of Refraction The law of refraction relates the angle of incidence (angle between the incident ray and the normal) to the angle of refraction (angle between the refracted ray and the normal). This law, credited to Willebrord Snell, states that the ratio of the sine of the angle of incidence, i, to the sine of the angle of refraction, r, is equal to the ratio of the speed of light in the original medium, vi, to the speed of light in the refracting medium, vr, or sin i/sin r=vi/vr. Snell's law is often stated in terms of the indexes of refraction of the two media rather than the speeds of light in the media. The index of refraction, n, of a transparent medium is a direct measure of its optical density and is equal to the ratio of the speed of light in a vacuum, c, to the speed of light in the medium: n=c/v.

Indexes of refraction are always equal to or greater than 1; for air, n=1.00029; for water, n=1.33. Using indexes of refraction, Snell's law takes the form sin i/sin r=nr /ni, or ni sin i=nr sin r. If the original medium is denser than the refracting medium (ni greater than nr), sin r will be greater than sin i. Thus, there will be some acute angle less than 90° for the incident ray corresponding to an angle of refraction of 90°. This angle of incidence is known as the critical angle. For angles of incidence greater than the critical angle, refraction cannot take place and the incident ray is instead reflected back into the original medium according to the law of reflection reflection, return of a wave from a surface that it strikes into the medium through which it has traveled. The general principles governing the reflection of light and sound are similar, for both normally travel in straight lines and both are wave phenomena. ..... Click the link for more information. (angle of reflection equals angle of incidence). This phenomenon is known as total internal reflection.

Applications of Refraction Refraction has many applications in optics and technology. A lens lens, device for forming an image of an object by the refraction of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or with one surface plane and the other curved. ..... Click the link for more information. uses refraction to form an image image, in optics, likeness or counterpart of an object produced when rays of light coming from that object are reflected from a mirror or are refracted by a lens. An image of an object is also formed when this light passes through a very small opening like that of a pinhole ..... Click the link for more information. of an object for many different purposes, such as magnification. A prism prism, in optics, a piece of translucent glass or crystal used to form a spectrum of light separated according to colors. Its cross section is usually triangular. The light becomes separated because different wavelengths or frequencies are refracted (bent) by different amounts ..... Click the link for more information. uses refraction to form a spectrum spectrum, arrangement or display of light or other form of radiation separated according to wavelength, frequency, energy, or some other property.

Beams of charged particles can be separated into a spectrum according to mass in a mass spectrometer (see mass spectrograph). ..... Click the link for more information. of colors from an incident beam of light. Refraction also plays an important role in the formation of a mirage mirage , atmospheric optical illusion in which an observer sees in the distance a nonexistent body of water or an image, sometimes distorted, of some object or of a complete scene. ..... Click the link for more information. and other optical illusions. refraction (ri-frak -shŏn) A phenomenon occurring when a beam of light or other wave motion crosses a boundary between two different media, such as air and glass. On passing into the second medium, the direction of motion of the wave is ‘bent’ toward or away from the normal (the line perpendicular to the surface at the point of incidence). The incident and refracted rays and the normal all lie in the same plane. The direction of propagation is changed in accordance with Snell's law: n 1 sin i = n 2 sin r i and r are the angles made by the incident and refracted ray to the normal; n 1 and n 2 are the refractive indices of the two media.

The change in direction of motion results from a change of wave velocity as the wave passes from the first to the second medium. Refraction The Russian words refraktsiia and prelomlenie may both be translated as “refraction.” When used with respect to light, refraktsiia in the broad sense has the same meaning as prelomlenie—that is, the change in the direction of light rays when the index of refraction of the medium through which the rays pass changes (see REFRACTION OF LIGHT ). For historical reasons, refraktsiia is more often used when characterizing the propagation of optical radiation in media whose index of refraction varies continuously from point to point; the paths of light rays in such media are smooth curves. The term prelomlenie is more often applied to the case where there is an abrupt change in the direction of light rays at the interface of two homogeneous media with different indexes of refraction. The term refraktsiia is by tradition used in a number of branches of optics, including atmospheric optics, eyeglass optics, and the optics of the eye. The eye is an optical system that refracts light.

A commonly used measure of the power of the eye as a refracting system is the eye’s power under suspension of accommodation. The principal refracting elements of the eye are the cornea and the lens. The power of these elements varies from 52.59 to 71.30 diopters; the average value is 59.92 diopters. In the normal, or emmetropic, eye, the power of the eye is matched to its dimensions. This means that parallel rays of light that enter the eye are focused at the center of the retina in the region of the macula lutea. A clear image of the object being viewed is then obtained on the retina—a situation that is a necessary condition for good vision. Errors in refraction result in myopia or hyperopia. The power of accommodation of the eye changes with age: it is less than normal in infants and may again decrease in old age. This change in accommodation power with advancing age is called presbyopia. Anomalies in refraction cannot be treated through medication. Special systems of optical lenses (eyeglasses) are used to correct vision when errors of refraction exist. refraction

Question: Refraction is the change of direction of a wave such as light due to change of its what when passing from one medium to another?
Answer: Speed