Merchant, F. W. (Francis Walter), 1855-1937, Chant, Clarence Augustus, 1865-1956 · Toronto : Copp Clark · leaf 336
ich falls perpendicularlyupon the surface, emergesas mA, in the same line.The rays on each side arerefracted as shown in thefigure, but the ray PB uponrefraction just skims along the surface. What becomes of a ray such as PC ? It cannot emerge into the air, and so it is refiiected back into the… … Fio. 370.—PB is the critical ray, and PBn (whichis equal to BPm) is the critical angle for waterand air. 326 REFRACTION is equal to BPm. Hence if the angle of incidence of anyray is greater than PBn it will suffer total reflection. Thisangle is called the critical angle which may be definedthus:—…
Physics
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