Henderson, C. Hanford (Charles Hanford), 1861-1941, Woodhull, John F. (John Francis), 1857-1941 · New York, D. Appleton and company · leaf 317
h scientific and practical importance. Since light, likeother commodities, is now bought and sold, people want toknow how much they are getting or giving. An instru-ment for measuring the intensity of light is known as aphotometer. We will consider only one. All methods ofmeasuring light depend on… … Photometer. on the screen. Each shadow, however, will be illuminatedby light coming from the other source. By having theshadows not too far apart, we may compare their intensitiesby the eye with fair accuracy. If the lights are placed atsuitable distances, the shadows may be made equally intense.…
Physics
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