Light for Students

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Macmillan, 1921 - Light - 579 pages
 

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Page 235 - And in like manner, when a Ray of Light falls upon the Surface of any pellucid Body, and is there refracted or reflected, may not Waves of Vibrations, or Tremors, be thereby excited in the refracting or reflecting Medium at the point of Incidence...
Page 235 - And are not these vibrations propagated from the point of incidence to great distances ? And do they not overtake the rays of light, and by overtaking them successively, do they not put them into the Fits of easy Reflection and Easy Transmission described above...
Page 328 - In ordinary cases of resistance, the main representative of the work apparently lost in propelling the solid is in the first instance the molecular kinetic energy of the trail of eddies in the wake. The formation of these eddies is however an indirect effect of the internal friction, or if we prefer the term — viscosity, of the fluid. Now the viscosity of gases has been explained on the kinetic theory of gases, and in the case of a liquid we cannot well doubt that it is connected with the constitution...
Page 325 - Argand lamp, from incandescent platinum, and even from non-luminous heated brass, through slices of tourmaline cut parallel to the axis of the crystal, a portion of the heat is polarized, when the axes of the crystals are at right angles to each other ; and these results were confirmed by M. Melloni. But Professor Forbes did not allow the polarization of heat to rest solely upon the results obtained with tourmaline. By employing bundles of plates of...
Page 328 - ... formation of these eddies is, however, an indirect effect of the internal friction, or if we prefer the term viscosity, of the fluid. Now the viscosity of gases has been explained on the kinetic theory of gases, and in the case of a liquid we cannot well doubt that it is connected with the constitution of the substance as not being absolutely continuous but molecular. But if the ether be either non-molecular, or molecular in some totally different sense from ponderable matter, we cannot with...
Page 305 - According to the wave theory of light, the index of refraction of a medium is equal to the ratio of the velocity of light in vacuum to that in the medium.
Page 342 - For if this hole be an inch or two long and but a tenth or twentieth part of an inch broad or narrower, the light of the image will be as simple as before, or simpler, and the image will become much broader and therefore more fit to have experiments tried in its light than before.
Page 490 - The laws of specular reflection are: (first law) the reflected ray lies in the same plane as the incident ray and the normal...
Page 58 - ... the three angles of a triangle are together equal to two right angles, although it is not known to all.
Page 463 - On now replacing the eyepiece by a camera, we are in position to photograph the spectrum with the greatest ease. We put in the sensitive plate, either wet or dry, and move to the part we wish to photograph. Having exposed for that part, we move to another position and expose once more. We have no thought for the focus, for that remains perfect, but simply refer to the table giving the proper exposure for that portion of the spectrum, and so have a perfect plate. Thus we can photograph the whole spectrum...

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