Phillips, Percy · London : T. C. & E. C. Jack ; New York : Dodge Pub. Co. · leaf 29
e re-flected wave-front is plane the rays, which are per-pendicular to the wave-front, are parallel and emergefrom the mirror in a narrow beam which does not spreadout. This is the principle of the search-light, which con-sists of a brilliant light placed at the focus of a parabolicmirror. The… … Fig. 12.the reflecting astronomical telescope. Light wavescoming from such distant sources as the astronomicalbodies are practically plane and are therefore broughtto a focus at the focus of a parabolic mirror. Animage of the body is therefore produced there. Refraction of Light. — When considering…
Light
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