Brechner, Claude H., 1887- [from old catalog] · Boston, New York [etc.] Allyn and Bacon · leaf 139
e this law, suppose a cardboard (a, Figure 119)is placed before a light (L), the cardboard having a smallhole in it. A second cardboard (6) with a square hole, oneinch on a side, cut in it is placed one foot from a. A thirdcardboard (c) is placed two feet from a. 127 128 ILLUMINATION AND CANDLE… … a b c Figure 119. — Explaining Law of Intensity of Illumination as theDistance Varies. Thus the light falls on an area at c, which is four times aslarge as on b; etc. Thus the area on which the light falls is directly proportionalto the square of the distance from the source. Since the intensity of…
Physics
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