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Refraction sentence examples

refraction
  • It is difficult to lay down rules for the treatment of cases where the refraction of the two eyes is unequal.

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  • There are perfect cleavages parallel to the rhombohedral faces, and the crystals exhibit a strong negative double refraction, like calcite.

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  • Since the angles of incidence and refraction are connected by the relation sin i=µ sin r (Snell's Law), µ being the index of refraction of the medium, then the problem may be stated as follows: to determine the value of the angle i which makes D = 2 (i - r) +n (7r - 2r) a maximum or minimum, in which i and r are connected by the relation sin i =µ sin r, µ being a constant.

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  • Soc., 1874, 22, p. 53 1) first pointed out that refraction would result from a variation in the temperature of the air at different heights.

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  • He discovered double refraction in Iceland spar (Experimenta crystalli islandici disdiaclastici, Copenhagen, 1669).

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  • The existence of internal strains in glass can be readil y recognized by examination in polarized light, any signs of double refraction indicating the existence of strain.

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  • The refraction spectra for different media also differ amongst themselves.

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  • This statement constitutes the famous hypothesis of Fresnel, which thus ensures that all phenomena of ray-path and refraction, and all those depending on phase, shall be unaffected by uniform convection of the material medium, in accordance with the results of experiment.

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  • The actual formation of On account of inequalities in the atmosphere giving a variable refraction, the light from a star would be irregularly distributed over a screen.

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  • The introduction of the idea that the phenomenon was caused by refraction is to be assigned to Vitellio.

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  • which does not consist of simple vibrations of a definite wave-length, undergoes refraction at the surface of any transparent medium, the different colours corre sponding to the different wave-lengths become separated or .dispersed.

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  • The most important subjects of his inquiries are enumerated by Forbes under the following five heads: - (1) The laws of polarization by reflection and refraction, and other quantitative laws of phenomena; (2) The discovery of the polarizing structure induced by heat and pressure; (3) The discovery of crystals with two axes of double refraction, and many of the laws of their phenomena, including the connexion of optical structure and crystalline forms; (4) The laws of metallic reflection; (5) Experiments on the absorption of light.

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  • A remarkable help to the cure of headaches and wider nervous disorders has come out of the better appreciation and correction of errors of refraction in the eye.

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  • He fell upon a most ingenious plan of doubling the amount of double refraction of a prism by using two prisms of rock-crystal, so cut out of the solid as to give each the same quantity of double refraction, and yet to double the quantity in the effect produced.

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  • He employed the law of refraction (discovered by W.

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  • If we compare the spectrum produced by refraction in a glass prism with that of a diffraction grating, we find not only that the order of colours is reversed, but also that the same colours do not occupy corresponding lengths on the two spectra, the blue and violet being much more extended in the refraction spectrum.

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  • Refraction of Sound.

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  • He concluded that there could be no refraction without dispersion, and hence that achromatism was impossible of attainment.

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  • According to the wave-theory of light, refraction is due to a change of velocity when light passes from one medium to another.

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  • The amount of separation is very small, and depends on the thickness of the glass, the index of refraction and the focal length of the telescope.

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  • This change of direction is termed refraction, and takes place, no doubt, according to the same laws as does the refraction of light, viz.

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  • Porphyritic crystals often contract less than the surrounding glass, which accordingly becomes strained, and in polarized light may show a weak double refraction in a limited area surrounding the crystal.

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  • A table of the atomic refractions and dispersions of the principal elements is here given: Dispersion and Composition.-In the preceding section we have seen that substances possess a definite molecular (or atomic) refraction for light of particular wave-length; the difference between the refractions for any two rays is known as the molecular (or atomic) dispersion.

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  • The refraction of light passing through sea-water is dependent on the salinity to the extent that the index of refraction is greater as the salinity increases.

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  • In his later book, Dioptrice (1611), he fully discusses refraction and the use of lenses, showing the action of the double convex lens in the camera obscura, with the principles which regulate its use and the reason of the reversal of the image.

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  • Stokes showed that this effect is one of refraction, due to variation of velocity of the air from the surface upwards Brit.

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  • It has in fact been found, with the very great precision of which optical experiment is capable, that all terrestrial optical phenomenareflexion, refraction, polarization linear and circular, diffraction - are entirely unaffected by the direction of the earth's motion, while the same result has recently been extended to electrostatic forces; and this is our main experimental clue.

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  • On the other hand, while in the older crown and flint glasses the relation between refraction and dispersion had been practically fixed, dispersion and refraction increasing regularly with the density of the glass, in some of the new glasses introduced by Abbe and Schott this relation is altered and a relatively low refractive index is accompanied by a relatively high dispersion, while in others a high refractive index is associated with low dispersive power.

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  • Cauchy, and succeeded in deducing laws of double refraction closely resembling those of A.

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  • Fermat, Roberval and Desargues took exception in their various ways to the methods employed in the geometry, and to the demonstrations of the laws of refraction given in the Dioptrics and Meteors.

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  • If the increase of the angle of refraction were proportional to the diminution of wave-length for a prism of any material, the resulting spectrum would also be normal.

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  • Similarly, by this method of differences, the atomic refraction of any element may be determined.

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  • 58-1.60, but the double refraction is very strong (o.04 - o.05) and is negative in sign.

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  • the production of pairs of glasses of widely differing refraction and dispersion, but having a similar distribution of dispersion in the various regions of the spectrum, was not in the first instance solved.

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  • When Mr Eyre viewed the country from Mount Deception in 1840, looking between Lake Torrens and the lake which now bears his own name, the refraction of light from the glittering crust of salt that covers a large space of stony or sandy ground produced an appearance of water.

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  • In his eighteenth year, while still a student in Edinburgh, he contributed two valuable papers to the Transactions of the same society - one of which, " On the Equilibrium of Elastic Solids," is remarkable, not only on account of its intrinsic power and the youth of its author, but also because in it he laid the foundation of one of the most singular discoveries of his later life, the temporary double refraction produced in viscous liquids by shearing stress.

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  • By this time he had ceased to devote himself to pure mathematics, and in company with his friends Mersenne and Mydorge was deeply interested in the theory of the refraction of light, and in the practical work of grinding glasses of the best shape suitable for optical instruments.

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  • He worked hard at his book on refraction, and dissected the heads of animals in order to explain imagination and memory, which he considered physical processes.'

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  • We will now consider the application of the principle to the formation of images, unassisted by reflection or refraction (Phil.

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  • Fraunhofer further initiated the specification of refraction and dispersion in terms of certain lines of the spectrum, and even attempted an investigation of the effect of chemical composition on the relative dispersion produced by glasses in different parts of the spectrum.

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  • In this line of investigation the prime importance belongs to the discovery (1) of the connexion between the refractive index and the polarizing angle, (2) of biaxial crystals, and (3) of the production of double refraction by irregular heating.

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  • But the investigation by which he reaches them has the merit of first prominently publishing and establishing the law of the refraction of light.

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  • The indices of refraction are not high, the mean index being about I.

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  • By subtracting the value for CH 2, which may be derived from two substances belonging to the same homologous series, from the molecular refraction of methane, CH 4, the value of hydrogen is obtained; subtracting this from CH 2, the value of carbon is determined.

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  • - Reference should be made to the article Refraction for the general discussion of the phenomenon known as the refraction of light.

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  • It is found, however, that the same element has not always the same atomic refraction, the difference being due to the nature of the elements which saturate its valencies.

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  • Bacon then discusses vision in a right line, the laws of reflection and refraction, and the construction of mirrors and lenses.

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  • Attempts have been made, principally founded on some remarks of Huygens, to show that Descartes had learned the principles of refraction from the manuscript of a treatise by Willebrord Snell, but the facts are uncertain; and, so far as Descartes founds his optics on any one, it is probably on the researches of Kepler.

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  • Refraction and Composition.

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  • I); let AD be the refracted ray, and r the angle of refraction.

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  • Glass or plastic filaments allow the internal refraction of light for viewing.

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  • refraction effect at the model length scale.

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  • It may be added that he first examined the conditions of stability of the system formed by Saturn's rings, pointed out the necessity for their rotation, and fixed for it a period (Io h 33 m) virtually identical with that established by the observations of Herschel; that he detected the existence in the solar system of an invariable plane such that the sum of the products of the planetary masses by the projections upon it of the areas described by their radii vectores in a given time is a maximum; and made notable advances in the theory of astronomical refraction (Mec. cel.

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  • The hexaiodide, S12161 is obtained by heating the tetraiodide with finely divided silver to 300° C. It crystallizes in hexagonal prisms which exhibit double refraction.

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  • Taylor gave (Methodus Incrementorum, p. 108) the first satisfactory investigation of astronomical refraction.

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  • - Biconcave, biconvex and concavo-convex (meniscus) lenses are employed in ophthalmic practice in the treatment of errors of refraction.

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  • Sarasin and longer series of experiments by Tornde and Kriimmel this relation is shown to be so close that the salinity of a sample can be ascertained by determining the index of refraction.

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  • This quantity may readily be expressed in terms of the refractive indices for the three colours, for if A is the angle of the prism (supposed small) bc=(/1c - I)A, bD =(/ AD - OA, F - I)A, where µc, A n, µ F are the respective indices of refraction.

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  • By studying the dispersion of colours in water, turpentine and crown glass Newton was led to suppose that dispersion is proportional to refraction.

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  • Thus if a horizontal slit is illuminated by an arc lamp, and the light - rendered parallel by a collimating lens - is transmitted through the sodium tube and focused on the vertical slit of a spectroscope, the effect of the sodium vapour is to produce its refraction spec trum vertically on the slit.

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  • A preliminary study of optics led to the publication, in 1604, of his Astronomiae pars optica, containing important discoveries in the theory of vision, and a notable approximation towards the true law of refraction.

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  • Appended were tables of logarithms and of refraction, together with Tycho's catalogue of 777 stars, enlarged by Kepler to 1005.

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  • Appended to the London edition of the solar and lunar tables are two short tracts - the one on determining longitude by lunar distances, together with a description of the repeating circle (invented by Mayer in 1752), the other on a formula for atmospheric refraction, which applies a remarkably accurate correction for temperature.

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  • The manuscript residue includes papers on atmospheric refraction (dated 1755), on the motion of Mars as affected by the perturbations of Jupiter and the Earth (1756), and on terrestrial magnetism (1760 and 1762).

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  • The difference between the coefficients o 97 and 1 17 arises from the refraction of the ray, but for which they would be equal.

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  • Hooke, in 1674, published his observations of y Draconis, a star of the second magnitude which passes practically overhead in the latitude of London, and whose observations are therefore singularly free from the complex corrections due to astronomical refraction, and concluded that this star was 23" more northerly in July than in October.

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  • If 1 2 and t l are thicknesses traversed by the extreme rays, t = t 2 - t,, and if, as is usually the case, the prism is filled right up to its refraction cap, = o, and t becomes equal to the greatest thickness of the medium which is made use of.

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  • - Spectroscopes may be divided into two classes: prism spectroscopes, with angular or direct vision, and grating spectroscopes; the former acting by refraction (q.v.), the latter by diffraction or interference.

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  • In physical science, a halo is a luminous circle, surrounding the sun or moon, with various auxiliary phenomena, and formed by the reflection and refraction of light by ice-crystals suspended in the atmosphere.

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  • Halos are at definite distances (22° and 46 °) from the sun, and are coloured red on the inside, being due to refraction; coronae closely surround the sun at variable distances, and are coloured red on the outside, being due to diffraction.

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  • Mariotte explained the inner halo as being due to refraction through a pair of alternate faces, since the minimum deviation of an ice-prism whose refracting angle is 60° is about 22°.

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  • Similarly, as explained by Henry Cavendish, the halo of 46° is due to refraction by faces inclined at 90°.

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  • The impurity of the colours (due partly to the sun's diameter, but still more to oblique refraction) is more marked in halos than in rainbows; in fact, only the red is at all pure, and as a rule, only a mere trace of green or blue is seen, the external portion of each halo being nearly white.

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  • The parhelia (p) were explained by Mariotte as due to refraction through a pair of alternate faces of a vertical prism.

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  • The "tangential arcs" (T) were explained by Young as being caused by the thin plates with their axes horizontal, refraction taking place through alternate faces.

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  • Similarly, the tangential arcs to the halo of 46° are due to refraction through faces inclined at 90°.

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  • This paper was followed by many others on diverse topics - on rain and dew and the origin of springs, on heat, the colour of the sky, steam, the auxiliary verbs and participles of the English language and the reflection and refraction of light.

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  • Theodolites are designed to measure horizontal angles with greater accuracy than vertical, because it is on the former that the most important work of a survey depends; measures of vertical angles are liable to be much impaired by atmospheric refraction, more particularly on long lines, so that when heights have to be determined with much accuracy the theodolite must be discarded for a levelling instrument.

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  • Crystals belonging to the cubic system should not be birefringent unless strained; diamond often displays double refraction particularly in the neighbourhood of inclusions, both liquid and solid; this is probably due to strain, and the spontaneous explosion of diamonds has often been observed.

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  • The substance is usually optically isotropic, though sometimes it exhibits anomalous double refraction; fibrous zinc sulphide which is doubly refracting is to be referred to the hexagonal FIG.

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  • Halite occasionally exhibits double refraction, perhaps due to natural pressure.

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  • A paper published in 1809 ("Sur une propriete de la lumiere reflechie par les corps diaphanes") contained the discovery of the polarization of light by reflection, which is specially associated with his name, and in the following year he won a prize from the Institute with his memoir, "Theorie de la double refraction de la lumiere dans les substances cristallines."

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  • Prior to Young, halos and coronae had not been clearly differentiated; they were both regarded as caused by the refraction of light by atmospheric moisture and ice, although observation had shown that important distinctions existed between these phenomena.

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  • of refraction.

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  • prop. 3) "that all refracting substances diverged the prismatic colours in a constant proportion to their mean refraction"; and he drew the natural conclusion "that refraction could not be produced without colour," and therefore "that no improvement could be expected from the refracting telescope" (Treatise on Optics, p. 112).

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  • this circle to measure the polar distance of any star seen in the telescope, and these readings will also be true (apart from the effects of atmospheric refraction) if we rotate the instrument through any angle on the axis A A.

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  • Further, by causing the hour circle, and with it the polar axis, to rotate by clockwork or some equivalent mechanical contrivance, at the same angular velocity as the earth on its axis, but in the opposite direction, the telescope will, apart from the effects of refraction, automatically follow a star from rising to setting.

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  • The peculiar form of the tube is eminently suited for rigid preservation of the relative parallelism of the axes of the two telescopes, so that,;i the image of a certain selected star is retained on the intersection of two wires of the micrometer, by means of the driving clock, aided by small corrections given by the observer in right ascension and declination (required on account of irregularity in the clock movement, error in astronomical adjustment of the polar axis, or changes in the star's apparent place produced by refraction), the image of a star will continue on the same spot of the photographic film during the whole time of exposure.

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  • NIU?II1010 which he has erected at Cambridge (Eng.) and applied to an investigation of the change of latitude and a determination of the constant of refraction.

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  • On his way home he saw the great bird Rukh (evidently, from his description, an island lifted by refraction); revisited Sumatra, Malabar, Oman, Persia, Bagdad, and crossed the great desert to Palmyra and Damascus, where he got his first news of home, and heard of his father's death fifteen years before.

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  • Atmospheric refraction causes the sun to be visible for periods varying from south to north for a quarter to half an hour after it has actually sunk below the horizon.

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  • white light), which is dispersed by refraction, and monochromatic (Gr.

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  • These authors proved, however, that no optical system can justify these suppositions, since they are contradictory to the fundamental laws of reflexion and refraction.

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  • If there be refraction at a collective spherical surface, or through a thin positive lens, 0' 2 will lie in front of O' 1 so long as the angle u2 is greater than u 1 (" under correction "); and conversely with a dispersive surface or lenses (" over correction ").

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  • This ray, named by Abbe a " principal ray " (not to be confused with the " principal rays " of the Gaussian theory), passes through the centre of the entrance pupil before the first refraction, and the centre of the exit pupil after the last refraction.

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  • The heights of peaks determined by exact processes of trigonometrical observation are bound to be more or less in error for three reasons: (1) the extraordinary geoidal deformation of the level surface at the observing stations in submontane regions; (2) ignorance of the laws of refraction when rays traverse rarefied air in snow-covered regions; (3) ignorance of the variations in the actual height of peaks due to the increase, or decrease, of snow.

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  • broad according to Zopf), highly refractive and colourless (or very dark, probably owing to the high index of refraction and minute size).

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  • Fluor-spar, though cubic, sometimes exhibits weak double refraction, probably due to internal tension.

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  • He taught, previous to the Polish physicist Witclo, that vision does not result from the emission of rays from the eye, and wrote also on the refraction of light, especially on atmospheric refraction, showing, e.g.

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  • Another discussed conduction in curved sheets; a third the distribution of electricity in two influencing spheres; a fourth the deter mination of the constant on which depends the intensity of induced currents; while others were devoted to Ohm's law, the motion of electricity in submarine cables, induced magnetism, &c. In other papers, again, various miscellaneous topics were treated - the thermal conductivity of iron, crystalline reflection and refraction, certain propositions in the thermodynamics of solution and vaporization, &c. An important part of his work was contained in his Vorlesungen fiber mathematische Physik (1876), in which the principles of dynamics, as well as various special problems, were treated in a somewhat novel and original manner.

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  • In optics, the term caustic is given to the envelope of luminous rays after reflection or refraction; in the first case the envelope is termed a catacaustic, in the second a diacaustic. Catacaustics are to be observed as bright curves when light is allowed to fall upon a polished riband of steel, such as a watch-spring, placed on a table, and by varying the form of the spring and moving the source of light, a variety of patterns may be obtained.

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  • The investigation of caustics, being based on the assumption of the rectilinear propagation of light, and the validity of the experimental laws of reflection and refraction, is essentially of a geometrical nature, and as such it attracted the attention of the mathematicians of the 17th and succeeding centuries, more notably John Bernoulli, G.

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  • The simplest instance of a caustic by refraction (or diacaustic) is when luminous rays issuing from a point are refracted at a straight line.

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  • For the caustic by refraction of parallel rays at a circle reference should be made to the memoirs by Arthur Cayley.

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  • In the article Refraction it is shown that a ray of light traversing a homogeneous medium is deviated from its rectilinear path when it enters a medium of different refractive index; it is therefore readily seen that the path of a ray through continuously varying media is necessarily curvilinear, being compounded of an infinite number of infinitesimally small rectilinear deviations.

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  • The indices of refraction of quartz for yellow (D) light are co = I.5442 and e = I.

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  • The line n shows the factor by which the index of refraction of the transmitted vibration is multiplied, and the curve p the intensity of the absorbed vibration for that wave-length.

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  • This singular result is still known by the name conical refraction," which he proposed for it when he first predicted its existence in the third supplement to his " Systems of Rays," read in 1832.

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  • In a small commonplace book, bearing on the seventh page the date of January 1663/1664, there are several articles on angular sections, and the squaring of curves and " crooked lines that may be squared," several calculations about musical notes, geometrical propositions from Francis Vieta and Frans van Schooten, annotations out of Wallis's Arithmetic of Infinities, together with observations on refraction, on the grinding of " spherical optic glasses," on the errors of lenses and the method of rectifying them, and on the extraction of all kinds of roots, particularly those " in affected powers."

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  • So that, were a glass so exactly figured as to collect any one sort of rays into one point, it could not collect those also into the same point, which having the same Incidence upon the same Medium are apt to suffer a different refraction.

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  • But these seemed very great difficulties, and I have almost thought them insuperable, when I further considered, that every irregularity in a reflecting superficies makes the rays stray 5 or 6 times more out of their due course, than the like irregularities in a refracting one; so that a much greater curiosity would be here requisite, than in figuring glasses for Refraction.

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  • The species of colour, and degree of Refrangibility proper to any particular sort of Rays, is not mutable by Refraction, nor by Reflection from natural bodies, nor by any other cause, that I could yet observe.

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  • Then place a Lens of about three foot radius (suppose a broad Object-glass of a three foot Telescope), at the distance of about four or five foot from thence, through which all those colours may at once be transmitted, and made by its Refraction to convene at a further distance of about ten or twelve feet.

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  • He succeeded in explaining the colour of thin and of thick plates, and the inflexion of light, and he wrote on double refraction, polarization and binocular vision.

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  • Among these subjects were the transit of Mercury, the Aurora Borealis, the figure of the earth, the observation of the fixed stars, the inequalities in terrestrial gravitation, the application of mathematics to the theory of the telescope, the limits of certainty in astronomical observations, the solid of greatest attraction, the cycloid, the logistic curve, the theory of comets, the tides, the law of continuity, the double refraction micrometer, various problems of spherical trigonometry, &c. In 1742 he was consulted, with other men of science, by the pope, Benedict XIV., as to the best means of securing the stability of the dome of St Peter's, Rome, in which a crack had been discovered.

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  • He further brought into prominence the effects of refraction in altering the apparent places of the heavenly bodies, and substituted Venus for the moon as a connecting-link between observations of the sun and stars.

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  • But this is not the true direction, because the ray of light from the object undergoes refraction in passing through the atmosphere.

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  • This is one of the most troublesome problems in astronomy because, owing to the ever varying density of the atmosphere, arising from differences of temperature, and owing to the impossibility of determining the temperature with entire precision at any other point than that occupied by the observer, the amount of refraction must always be more or less uncertain.

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  • The uncertainty thus arising in the amount of the refraction is least near the zenith, but increases more and more as the horizon is approached.

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  • The most delicate indication of an atmosphere would be through the refraction of the light of a star when seen coincident with the limb of the moon.

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  • Its elevation as at present determined by trigonometrical observation is 2 9, 002 ft., but it is possible that further investigation into the value of refraction at such altitudes will result in placing the summit even higher.

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  • The phenomenon of polarization observed by Huygens remained an isolated fact for over a century, until Malus in 1808 discovered that polarization can be produced independently of double refraction, and must consequently be something closely connected with the nature of light itself.

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  • Malus that the interposition of a doubly refracting plate between a polarizer and an analyser regulated for extinction has the effect of partially restoring the light, and he used this property to discover double refraction in cases in which the separation of the two refracted streams was too slight to be directly detected.

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  • In strictness the angle is dependent upon the frequency, but if the dispersion be weak relatively to the double refraction, the product sin 24 - a)sin 2Ni - (3) has sensibly the same value for all terms of the summation, and we may write I=cos 2 (1 3 - a)/a 2 - sin 2 (1 ' - a) sin 2 (t ' - a 2 sin 2 2 This formula contains the whole theory of the colours of crystalline plates in polarized light.

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  • In this way a delicate test for slight traces of double refraction is obtained.

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  • But as this surface is obtained by assuming that the interfering streams follow the same route in the crystal, and by neglecting the refraction out of the crystal, it does not lend itself to accurate numerical calculations.

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  • Thus a bar of glass of sufficient thickness, placed in the diagonal position between a crossed polarizer and analyser and bent in a plane perpendicular to that of vision, exhibits two sets of coloured bands separated by a neutral line, the double refraction being positive on the dilated and negative on the compressed side.

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  • Since the two circular streams have different speeds, Fresnel argued that it would be possible to separate them by oblique refraction, and though the divergence is small, since the difference of their refractive indices in the case of quartz is only about o 00007, he succeeded by a suitable arrangement of alternately rightand left-handed prisms of quartz in resolving a plane-polarized stream into two distinct circularly polarized streams. A similar arrangement was used by Ernst v.

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  • 149) has shown that the results deduced from Airy's waves of permanent type may be obtained by regarding the action of the medium as the superposition of the effects of ordinary double refraction and of an independent rotary power.

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  • - Huygens satisfactorily explained the laws of reflection and refraction on the principles of the wave theory, so far as the direction of the waves is concerned, but his explanation gives no account of the intensity and the polarization of the reflected light.

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  • This was supplied by Fresnel, who, starting from a mechanical hypothesis, showed by ingenious but not strictly dynamical reasoning that if the incident stream have unit amplitude, that of the reflected stream will be - sin (i - r) /sin (i -{- r) or tan (i - r) /tan (i -{- r), according as the incident light is polarized in or perpendicularly to the plane of incidence i, r, being the angles of incidence and refraction connected by the formula sin i =,u sin r.

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  • Fresnel obtained his formulae by assuming that the optical difference of media is due to a change in the effective density of the ether, the elasticity being the same - an assumption inconsistent with his theory of double refraction - and was led to the result that the vibrations are perpendicular to the plane of polarization.

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  • It was at first supposed that the defect of Fresnel's formulae was due to the neglect of the superficial undulations that, on a rigorous elastic solid theory of the ether, are called into existence at reflection and refraction.

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  • The best method of obtaining a strong beam of polarized light is to isolate one of the streams into which a beam of common light is resolved by double refraction.

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  • A rumour of the new invention, which reached Venice in June 1609, sufficed to set Galileo on the track; and after one night's profound meditation on the principles of refraction, he succeeded in producing a telescope of threefold magnifying power.

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  • The diamond has the requisite optical properties, its index of refraction being about i 6 times as large as that of ordinary glass.

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  • With this mineral also spherical and chromatic aberration are a fraction of that of a glass lens, but double refraction, which involves a doubling of the image, is fatal to its use.

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  • Axial aberration is reduced by distributing the refraction between two lenses; and by placing the two lenses farther apart the errors of the pencils of rays proceeding from points lying outside the axis are reduced.

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  • If the value of the clearness in air be taken as sin u1, then by the law of refraction N =sin u l /sin u2, the value for the clearness in water is N sin u 2.

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  • Schott succeeded, however, in producing glasses which with a comparatively low refraction have a high dispersion, and with a high refraction a low dispersion.

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  • assumed for simplicity that water and glass have identical coefficients of refraction.

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  • AtmDCC An atmospheric dispersion compensator and field corrector (AtmDCC) is required to correct for atmospheric refraction and field curvature.

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  • However it is easy to separate with an eye glass, having a large double refraction.

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  • index of refraction is greater for the shorter wavelength, violet light is bent the most and red the least as indicated.

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  • magnifyke a green flash these tiny refraction effects need somehow to be considerably magnified.

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  • Soe that blew rays suffer a greater refraction then red ones.

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  • Light rays from a distant object are almost parallel so do not need much refraction to focus onto the retina.

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  • The research showed that reflectance and luminosity of fire escape signage is affected by light refraction in smoke conditions.

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  • This is an illusion caused by the refraction of light within the resin.

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  • Cirrus is a nearly unique source of these displays because they are produced by the refraction of light-rays passing through ice crystals.

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  • The blurring evident in the image is thought to result from atmospheric refraction.

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  • The methods are seismic refraction, gravity and electrical resistivity.

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  • In 1833 Hamilton announced his discovery of conical refraction of light.

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  • differential refraction pushes the lower limb upwards to create the highly flattened shape.

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  • refraction index of the optical fiber.

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  • refraction analysis should then be undertaken to determine the specific climates for the selected beaches.

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  • The main benefit would be to provide more precise input to modeling of the contribution of wave refraction to inshore wave climate.

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  • refraction of the rays occurs on the glass - water boundaries.

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  • refraction of light for viewing.

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  • refraction of sunlight by the Earth's atmosphere.

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  • (21) a formula giving the coefficient of transmission in terms of the refraction, and of the number of particles per unit volume.

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  • Of lost works by Archimedes we can identify the following: (I) investigations on polyhedra mentioned by Pappus; (2) Archai, Principles, a book addressed to Zeuxippus and dealing with the naming of numbers on the system explained in the Sand Reckoner; (3) Peri zygon, On balances or levers; (4) Kentrobarika, On centres of gravity; (5) Katoptrika, an optical work from which Theon of Alexandria quotes a remark about refraction; (6) Ephodion, a Method, mentioned by Suidas; (7) Peri sphairopeoia, On Sphere-making, in which Archimedes explained the construction of the sphere which he made to imitate the motions of the sun, the moon and the five planets in the heavens.

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  • 2 For the corrections applicable to measures of position-angle in different hour angles, on account of errors of the equatorial instrument and of refraction, see Chauvenet's Practical and Spherical Astronomy, ii.

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  • One drawback to this form of instrument is that the two webs cannot be viewed simultaneously, and therefore the observer must rely on the steadiness of rate of the clockwork and uniformity in the conditions of refraction whilst the eye is moved from one eyepiece to the other.

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  • An originally unanticipated difficulty has arisen from the fact that the reseau-lines have not been ruled on plates of optical glass with optical surfaces, and that, in consequence of irregular refraction in the glass plate, the rays do not always pass through the silver film-lines in a direction strictly normal to the silvered surface; therefore, if the sensitive surface of the photographic plate is not in contact with the silver film of the reseau, the undeveloped photographic copy of the reseau may in such a case not be an exact reproduction of the silvered reseau.

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  • In his Memoire sur le refraction des corps solides (1741) he was the first to give a theoretical explanation of the phenomenon which is witnessed when a body passes from one fluid to another more dense in a direction not perpendicular to the surface which separates the two fluids.

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  • Few will be inclined to dispute the verdict of Forbes: - "His scientific glory is different in kind from that of Young and Fresnel; but the discoverer of the law of polarization of biaxial crystals, of optical mineralogy, and of double refraction by compression, will always occupy a foremost rank in the intellectual history of the age."

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  • The deviation is thus seen to vary with the angle of incidence; and by considering a set of parallel rays passing through the same principal plane of the sphere and incident at all angles, it can be readily shown that more rays will pass in the neighbourhood of the position of minimum deviation than in any other position (see Refraction).

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  • In accordance with a general consequence of reflection and refraction, it is readily seen that the light of the rainbow is partially polarized, a fact first observed in 1811 by Jean Baptiste Biot (see Polarization).

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  • Refraction and Dispersion.-The purely optical properties of refraction and dispersion, although of the greatest importance, cannot be dealt with in any detail here; for an account of the optical properties required in glasses for various forms of lenses see the articles Lens and Aberration: Ii.

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  • The hexaiodide, S12161 is obtained by heating the tetraiodide with finely divided silver to 300° C. It crystallizes in hexagonal prisms which exhibit double refraction.

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  • 'iii., 1801, pp. 169-198) is due the happy idea of applying the two images formed by double refraction to the construction of a micrometer.

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  • (A later recalculation gave 57,033 toises =121,569 yds., after the application of some corrections to the measures indicated by himself.) Snell also distinguished himself as a mathematician, and discovered the law of refraction, in 1621 (see Light).

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  • The explanation of the colours of the rainbow, which are also due to dispersion, was given by Newton, although it was known previously to be due to refraction in the drops of rain (see Rainbow).

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  • He concluded that there could be no refraction without dispersion, and hence that achromatism was impossible of attainment (see Aberration).

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  • Halos are at definite distances (22° and 46 °) from the sun, and are coloured red on the inside, being due to refraction; coronae closely surround the sun at variable distances, and are coloured red on the outside, being due to diffraction.

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  • If innumerable numbers of such crystals fall in any manner between the observer and the sun, light falling upon these crystals will be refracted, and the refracted rays will be crowded together in the position of minimum deviation (see Refraction Of Light).

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  • Mariotte explained the inner halo as being due to refraction through a pair of alternate faces, since the minimum deviation of an ice-prism whose refracting angle is 60° is about 22°.

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  • Similarly, as explained by Henry Cavendish, the halo of 46° is due to refraction by faces inclined at 90°.

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  • Similarly, the tangential arcs to the halo of 46° are due to refraction through faces inclined at 90°.

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  • The lustre is resinous to adamantine, and the index of refraction high (2.369 for sodium light).

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  • Early in 1757 he succeeded in producing refraction without colour by the aid of glass and water lenses, and a few months later he made a successful attempt to get the same result by a combination of glasses of different qualities (see Telescope).

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  • Reference should be made to the articles Reflexion, Refraction, and Caustic for the general characters of reflected and refracted rays (the article Lens considers in detail the properties of this instrument, and should also be consulted); in this article will be discussed the nature, varieties and modes of aberrations mainly from the practical point of view, i.e.

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  • Since the index of refraction varies with the colour or wave length of the light (see Dispersion), it follows that a system of lenses (uncorrected) projects images of different colours in somewhat different places and sizes and with different aberrations; i.e.

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  • The first variation must be taken into account in correcting geodetic observations of heights and astronomical observations of the heavenly bodies; it also has a considerable bearing on the phenomena of the twilight and the afterglow (see Refraction: § Astronomical; and Twilight).

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  • The examination of dispersion of the optic axes in biaxal crystals (see Refraction, § Double) may be conveniently made with a plate perpendicular to the acute bisectrix placed in the diagonal position for light of mean period between a crossed polarizer and analyser.

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  • As regards the course - of the streams on refraction into the crystal, it is found that it is determined by the Huygenian law (see Refraction, § Double); as, however, the two streams in the direction of the axis have different speeds, the spherical and the spheroidal sheets of the wavesurface do not touch as in the case of inactive uniaxal crystals.

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  • Besides this there is a second point on the axis, from which all issuing rays are so refracted at the surface of the sphere that, after the refraction, they appear to originate from one point - the image-point (see fig.

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  • He used chiefly a highly curved piano-convex front lens, which has since always been employed in strong systems. Even if the object-point on the axis cannot be reproduced quite free from aberration through such a lens, because aberrations of the type of an under-correction have been produced by the first plane outer limiting surface, yet the defects with the strong refraction are relatively small and can be well compensated by other systems. Amici chiefly employed cemented pairs of lenses consisting of a plano-convex flint lens and a biconvex crown lens(fig.

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  • Refraction All materials refract light (alter its angle).

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  • Differential refraction pushes the lower limb upwards to create the highly flattened shape.

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  • This results in a permanent change in the periodic refraction index of the optical fiber.

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  • There is no major refraction effect at the model length scale.

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  • A shoaling and refraction analysis should then be undertaken to determine the specific climates for the selected beaches.

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  • With a water immersion lens however, refraction of the rays occurs on the glass - water boundaries.

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  • These are partly formed because of the refraction of the waves around the end of the spit.

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  • This color results from the refraction of sunlight by the Earth 's atmosphere.

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  • Light refraction: Using a flashlight and a kitchen sink, students can test how light refracts at different levels of water.

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  • Students will add or remove more water from the sink and see how the light refraction changes at these levels.

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  • This refraction is enough to cause a visual distortion or eye fatigue.

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  • This technological advance was developed when researchers found that the standard sunglass curve caused refraction that led to headaches and vision distortion.

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  • The shape and thickness of the Spy lens combats this problem by eliminating the refraction.

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  • To be suitable for eyeglass lenses, a material must be transparent, without bubbles, and have a high index of refraction.

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  • The greater the index of refraction, the thinner the lens can be.

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  • The crown glass used for eyeglass lenses has an index of refraction of 1.52.

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  • Myopia is diagnosed by determining a child's unaided vision and is confirmed objectively by the eye care practitioner with various techniques, including retinoscopy and refraction.

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  • There is a sacrifice to that optical illusion, however: longer diamond shapes tend to have less brilliance and may reflect shadows or dark spots in their interior because of the irregular reflection and refraction patterns.

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  • Reflection Colors: Because of the precise index of refraction of a diamond, the shadows and shades reflected within a real stone will be shades of gray.

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  • Included diamonds are typically less brilliant than the other grades, since the flaws may affect the diamond's light refraction.

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  • Most jewelers avoid bezel settings for these stones because they don't take advantage of the elaborate faceting and light refraction of this cut.

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  • This variation on the original Asscher cut was the result of computer modeling to improve light refraction.

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  • Today the Royal Asscher Company is run by Edward and Joop Asscher who introduced a new version of the cut in 2001 based on Joseph's original designs and current computer technology that improved light refraction for a stone full of shine.

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  • The effect of the step cuts and deep culet creates more fire and internal refraction than other step diamond cuts.

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  • refraction All materials refract light (alter its angle ).

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  • refraction of the waves around the end of the spit.

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  • Fresnel; and in subsequent years he attacked the problem of giving mathematical expression to the conditions holding for a surface separating two crystalline media, and worked out from theory the laws of double refraction in strained crystalline bodies.

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  • Continuing his inquiries for the next year or two, he was able to discover the progressive propagation of electromagnetic action through space, to measure the length and velocity of electromagnetic waves, and to show that in the transverse nature of their vibration and their susceptibility to reflection, refraction and polarization they are in complete correspondence with the waves of light and heat.

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