Nettleship, Edward, 1845-1913 · Philadelphia ; New York : Lea brothers & co. · leaf 26
“ pebble” of opticians, 1.66, such a number is the “refractive index” of the substance. Every ray is refracted except the one which falls perpendicularly to the surface, Fig. 1, a. 3. In passing from a less into a more refractive medium the deviation is always toward the perpendicular to the… … Refraction by a medium with parallel sides. 4. Hence, if the sides of the medium, Fig. 1, m, be par¬ allel, the rays on emerging (&') are restored to their original direction (6), and, if the medium be thin, very nearly to their original path. 5. But if, as in a prism, the sides of m form an angle,…
Eye -- Diseases · Color blindness
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