Brechner, Claude H., 1887- [from old catalog] · Boston, New York [etc.] Allyn and Bacon · leaf 106
SHADOW FROM A LARGE SOURCE 95 shows the shadow cast by an object (0) with a large sourceof light (S). It will be seen that the space above be and below ad islighted by all of S. The space between ac and bd beyondthe object gets no light at all, and so is totally dark. Thisis called the umbra (U).… … Figure 70. — Shadow from a Large Source of Light. and still inside ad and be, is called the penumbra (P, P).This space is totally dark at ac and bd, but becomes lighterand lighter, as you go outward. That is, point y has morelight than point x, because more of S is shining on it. Shadows play a…
Physics
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