Johnson's natural philosophy and key to philosophical charts : illustrated with 500 cuts; being reduced photographic copies of all the diagrams contained in the author's philosophical series of indestructible school charts ; for the use of schools and families (1878)
aces (392). 392. Figure 21.—Paraboloid reflectors.—The nature of aparabolic curve is such that rays parallel to its axis will be reflected tOa single point, called i\\Q focus. Let F be the focus, and the lines FXand HN will form equal angles with the mirror, and the line, NH, willbe parallel to the… … OPTICS. 217 to any point of the reflect- Ffg. 21. or, as LN, the angle of in-cidence, HNL, will equalthe angle of reflection,FNL. If the lines parallel tothe axis be intersected bya line perpendicular to theaxis, then each of the par-allel lines plus its reflectedline, as HN plus NF, willequal each…
Physics · Astronomy
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