Ray (physics)

“ Hopefully no one finds it problematic, that I treat a light ray almost as a ponderable body. That light rays possess all absolute properties of matter, can be seen at the phenomenon of aberration, which is only possible when light rays are really material. — And furthermore, we cannot think of things that exist and act on our senses, without having the properties of matter. ”

“ It has already been mentioned that a ray of light flits through space at the rate of 1,000,000,000 feet, or nearly 186,500 miles a second. By suitable and very ingenious arrangements, physicists have been able to measure the velocity of electric radiation, and have found in every case that its velocity of propagation is precisely the same as a ray of light. ”

“ A ray of light may, for our purposes, be presented to the mind as a luminous straight line. Let such a ray be supposed to fall vertically upon a perfectly calm water-surface. The incidence, as it is called, is then perpendicular, and the ray goes through the water without deviation to the right or left. In other words, the ray in the air and the ray in the water form one continuous straight line. But the least deviation from the perpendicular causes the ray to be broken, or "refracted," at the point of incidence. What, then, is the law of refraction discovered by Snell? ”

“ The symmetry also requires that the intensity of the scattered light should vanish for the ray which would be propagated along the axis; for there is nothing to distinguish one direction transverse to the ray from another. We have now got what we want. Suppose, for distinctness of statement, that the primary ray is vertical, and that the plane of vibration is that of the meridian. The intensity of the light scattered by a small particle is constant, and a maximum for rays which lie in the vertical plane running east and west, while there is no scattered ray along the north and south line. ”

“ It is much better explained by supposing their eyes to be constructed to respond to wave-lengths either greater or less than those of mankind.
A ray of light, then, consists of a single line of undulations of a definite wave length, such that if it falls upon the eye it will produce sight; if it falls upon a thermo-pile it heats it by just the same quantity that another wave-length would heat it; if it falls upon matter in unstable chemical relations, it will do chemical work, depending upon the kinds of matter. A red ray is as effective for some substances as a violet ray is for others. ”

“ Newton states that he does not inquire, but suggests, for those who wish to deal in hypotheses, that the rays of light striking the bodies set up waves in the reflecting or refracting substances which move faster than the rays, and overtake them. When a ray is in that part of a vibration which conspires with its motion, it easily breaks through the refracting surface, and is in a fit of easy transmission; and, conversely, when the motion of the ray and the wave are opposed, the ray is in a fit of easy reflection. ”

“ It has here, practically the same fault which the artificial matter had on your world.
"As I see it, the ray is actually a directed gravitational field.
"Now here is one thing that makes it more interesting, and more useful. It seems to defy the laws of mechanics. It acts, but there is no apparent reaction! A small ship can swing a world! Remember, the field that generates the attraction is an integral, interwoven part of the mesh of Space. It is created by something outside of itself. Like the artificial matter, it exists there, and there alone. ”

“ It can also be proved by direct optical experiment that two rays of light, circularly-polarized in opposite directions, and of the same intensity, become, when united, a plane-polarized ray, and that if by any means the phase of one of the circularly-polarized rays is accelerated, the plane of polarization of the resultant ray is turned round half the angle of acceleration of the phase. ”

“ In all these substances, however, if the plane of polarization of any ray is twisted within the medium like a right-handed screw, it will still be twisted like a right-handed screw if the ray is transmitted through the medium in the opposite direction. The direction in which the observer has to turn his analyser in order to extinguish the ray after introducing the medium into its path, is the same with reference to the observer whether the ray comes to him from the north or from the south. The direction of the rotation in space is of course reversed when the direction of the ray is reversed. ”

“ Since the figure of the trajectory is now specified, we can consider the light ray again as arriving. And because I at first want to specify only the maximum of the perturbation angle, I assume that the light ray comes from an infinitely great distance. — The maximum must take place in this case, because the attracting body longer acts on the light ray when it comes from a greater than from a smaller distance. — If the light ray comes from an infinite distance, then its initial direction is that of the asymptote BR (Fig. 3.) ”

“ For the ray has really travelled from C to E, and from E to O, and it is that journey which determines the distance of the object; and hence we see ourselves as far beyond the mirror as we stand from it. Though a ray is here taken only from one part of the face, it may be easily 85 conceived that rays from every other part of the face must produce a similar effect. ”

“ The position of a ray in the spectrum depends solely on the wave-length of the light. It follows that the rays produced by any substance will be displaced toward the blue or red end of the spectrum, according as the body emitting or absorbing the rays is moving towards or from us. This method of determining the motions of stars to or from us, or their velocity in the line of sight from us to the star, was first put into practice by Mr.—now Sir William—Huggins, of London. ”

“ The "ray" in geometric optics is an abstraction, or "instrument", that can be used to predict the path of light. - "can be used" or "is used"? is used. ScienceApologist (talk) 20:23, 20 April 2009 (UTC) A light ray is a ray that is perpendicular to the light's wavefronts (and therefore collinear with the wave vector) . - 1) A ray is a ray? Usually we try not to repeat the word itself in the definition, as the definition is supposed to clarify to the uninitiated. 2) I am unsure what "collinear with the wave vector" means. A "light ray" is a "geometrical ray". ”

“ Light is thrown out on all sides from a luminous body like the spokes of a cart-wheel, and in the absence of any obstruction, the rays are distributed equally on all sides, diverging like the radii drawn from the centre of a circle. As a natural consequence arising from the divergence of each ray from the other, the intensity of light decreases as the distance from the luminous source increases, and vice versâ. ”

“ It requires only the most elementary ideas of geometry to see that if we suppose a ray of light to shoot from a star at such a distance in a direction perpendicular to the line of sight from us to the star, we can compute how fast the ray would seem to us to travel. ”

“ The plane-polarized ray may be regarded as the resultant of two circularly-polarized rays, one right and the other left handed, the former of which has a higher refractive index for the medium than the latter, if the rotation is towards the right, and a less, if the rotation is towards the left. ”

“ Moreover, if any transparent medium increases in density with depth, the amount of refraction will increase as the ray goes deeper, and the direction of the ray will be changed from a straight line into a curve, tending to become more and more perpendicular. ”

“ In general, rays of light falling obliquely on any medium are bent as if they were attracted by it, when it has a greater density, or contains more of the inflammable principle, than the medium through which it was transmitted to it. More of the rays are reflected when they fall upon a body with a small degree of obliquity to its surface, and more of them are transmitted, or enter the body, when their incidence is nearer to a perpendicular. ”

“ Ordinary light—according to the undulatory theory—is due to vibrations transverse to the direction of the ray, but varying so rapidly as to show no particular direction of their own, the fronts of the light-waves crisscrossing at all angles. ”

“ Theory of Optical Representation.—If a pencil of rays, i.e. the totality of the rays proceeding from a luminous point, falls on a lens or lens system, a section of the pencil, determined by the dimensions of the system, will be transmitted. The emergent rays will have directions differing from those of the incident rays, the alteration, however, being such that the transmitted rays are convergent in the “image-point,” just as the incident rays diverge from the “object-point.” With each incident ray is associated an emergent ray; such pairs are termed “conjugate ray pairs.” ”

“ It must, however, be remembered that rays have no physical existence, for it is the waves that are propagated, and not the ray, which simply indicates the direction that the light takes, this truth being known as the rectilineal propagation of light. That light proceeds in straight lines may be proved in several ways. For example, we cannot see round corners, which would be possible if light took a curved path instead of a straight one. ”

“ From experiments wherein a particles are allowed to escape freely, and again restrained by a lead cylinder surrounding radium, much of the apparent heat of the latter body appears to be due to the impinging of the a rays upon the surrounding surfaces.
-Rays are similar to cathode rays; they are less absorbable than the variety, and proceed at various speed, many approaching the velocity of light; they are stopped by solids in proportion to their density. ”

“ This the author calls the equation of the wave-surface or surface of ray-velocities. It has the form of the equation of FresneUs wave-surface, expressed in terms of the direction-cosines and reciprocal of the radius vector, and if are the direction-cosines of the ray, and the velocity of light in vacuo divided by the so-called ray-velocity in the crystal the equation will express Fresnel's law. ”

“ As a ray of light continues a ray of light so long as it exists in free ether, so all kinds of radiations, of whatever wave-length, continue identical until they fall upon some mechanical structure called matter. ”

“ A ray of plane-polarized light is transmitted through a transparent diamagnetic medium, and the plane of its polarization, when it emerges from the medium, is ascertained by observing the position of an analyser when it cuts off the ray. ”

“ When the deviated rays are convergent, the receiver is simply placed behind the shields, at the focus of the rays. But when the rays are parallel, the use of an objective (placed behind the first shield) gives very satisfactory results. As objectives I used ordinary glass lenses; knowing the index from my experiments, I was able to calculate the focal distance for the electric ray. ”

“ Sometimes one, and sometimes a quick succession of luminous currents run from one end of the arc or bow to the other, so that the rays rapidly increase in brightness; but it is impossible to say whether the coruscations themselves are actually affected by a horizontal motion of translation, or whether the more vivid light is conveyed from ray to ray. The rays occasionally dart far past the zenith, vanish, suddenly reappear, and, being joined by others from the arc, form a magnificent corona or immense dome of light. ”

“ A ray cuts the surface generally in more than one point; hence it will happen that some of the rays touch the surface, if two of these points coincide. The points of contact of these rays will form some curve on the surface, and this will appear from the centre of projection as the boundary of the surface or of part of the surface. The outlines of all surfaces of solids which we see about us are formed by the points at which rays through our eye touch the surface. ”

“ It is hardly necessary to occupy time with experiments in showing that a ray of light can be reflected and refracted by mirrors and prisms, and converged or diverged by transparent lenses. These are simple optical facts, and if you are not familiar with them it will be easy for you to make their acquaintance by studying any simple book upon optics; but I should like to draw your attention to the fact that, in addition to rays of light and electric radiation, we are acquainted with another kind of radiation, which is also susceptible of being refracted, and that is commonly called dark heat. ”