Carhart, Henry S. (Henry Smith), 1844-1920 · Boston : Allyn and Bacon · leaf 243
232 LIGHT. penumbra. This is limited by the double cone with its apexbetween the luminous and the opaque bodies (Fig. 99). This region of par-tial shadow forms thetransition from complete obscurity tothe full light. Thesmaller the angular dimensions of the source Fig. 99. and the nearer the screen…
Physics
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