r the lens atits principal axis are refracted to a focus more remote or nearerthe lens that those which enter at its edge. This imperfection iscalled the spherical aberration of lenses. 289. Let L M, Fig. 38, be a plano-convex lens with its planesurface exposed to the parallel rays B L, C K, D P, E… … near the edge of the lens ; it will be found upon tracing theircourse by the rules before laid down, that they meet in a focus,/, much nearer the lens than F. Let the raysitf/and Lfhe con-tinued till they meet G H, & plane perpendicular to the line ji F,then The distance Ff is called the…
Physics
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