An Elementary Treatise on OpticsG.Y. Van Debogert, 1852 - 261 من الصفحات |
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aberration achromatic angle of incidence aperture arcs axis beam called centre coincide concave consequently considered converging convex lens crown glass crystal dark denoting determined deviation diminishes direction dispersive powers distance of distinct distinct vision diverging double refraction elementary rays emanating emerge equal equation ether evidently extraordinary ray eye-glass flint glass foci formed fringes glass greater hence incident ray index of refraction intensity inverted length lenses less luminous point magnified maximum medium mirror molecules object oblique optic optic axis ordinary ray parallel pencil of light perpendicular plane of incidence plane of polarization plate polarized light position primary colors principal focal distance principal focus principal section prism produced propagated reflected rays refracting angles retina right angles rings screen semi-undulation spherical spherical aberration straight line stripes substances supposed surface tang telescope thickness tion tourmaline undulations velocity vibration wave
مقاطع مشهورة
الصفحة 31 - ... that the ratio of the sines of the angles of incidence and refraction is constant for refraction in the same medium, was effected by Snell and Descartes.
الصفحة 154 - Almost all scientific men, at the present day, believe that the particles of a luminous body are in a state of...
الصفحة 240 - ... their planes of polarization are at right angles to one another ; hence, a pile of panes of glass will give a polarized beam by refraction. For if a ray of common light pass through them, part of it will be polarized by the first...
الصفحة 30 - When a ray of light passes from one medium into another, it usually traverses it with a change of direction. But the respective densities of the two media may be such that, for a given angle of incidence, refraction is no longer possible.
الصفحة 132 - ... mirror, which, if the aperture be sufficiently large, may be viewed directly by means of an eye-piece placed in a suitable position, as in the case of the telescopes previously described. Such is the principle of Sir W. Herschel's telescope, which is the simplest of the reflecting telescopes. In order that the head of the observer may intercept as little light as possible, the axis of the mirror is slightly inclined to the axis of the tube in which it is fixed, and thus the image is thrown near...
الصفحة ii - Entered according to Act of Congress, in the Office of the Clerk of the Northern District of the State of New-York, August, 1852.
الصفحة 111 - ... the white letters will appear larger, and be read at a greater distance, than the black. This is owing to what is called the irradiation of light. It depends on this, that the impression made on the bottom of the eye by bright objects extends a little wider than the actual portion of...
الصفحة 71 - No. 768 deviation of a ray passing through a prism in a principal plane is a minimum when the angles of incidence and emergence are equal (§ 134) is much more elegant than any we have seen before.
الصفحة 117 - R'EW' nearly as RW to R'W'; so that the visual angle is enlarged in the ratio of the distance of distinct vision to the focal length of the lens. A convex lens, from the property it possesses of enlarging the apparent size of objects, is called a magnify ing-glass or a single microscope.
الصفحة 95 - Fig. 94*. objective. 92. Examples of compensated lens system, — (a) Telescopic objectives are used for very small field angle and they are therefore compensated only for spherical aberration and chromatic aberration. The achromatization is accomplished by using a converging lens of crown glass and a diverging lens of flint glass as explained in Art. 94. The condition which must be satisfied to produce achromatism [see equation (12), Art. 94] leaves some freedom of choice as to the relative curvatures...