. The Ontario high school physics. Fig. 431.—Illustrating the action of the simplemioiosLope. 362 OPTICAL INSTRUMENTS. Fig. 432.—The magnification is the ratio of pq toPQ- 415. Magnifying- Power of Simple Microscope. Let us find the magnification. The apparent size of an object is determined by_ the .size of the angle subtended t ---. at the eye by the object. Con- sider tlie eye to coincide inposition with the lens. Thenin Fig. 432 the angle sub-tended at the eye by the objectPQ is POQ, tliat subtended])y the \a.^e pq\^pOq. Theseangles are identical and atfirst sight we might thinkthere was n
. The Ontario high school physics. Fig. 431.—Illustrating the action of the simplemioiosLope. 362 OPTICAL INSTRUMENTS. Fig. 432.—The magnification is the ratio of pq toPQ- 415. Magnifying- Power of Simple Microscope. Let us find the magnification. The apparent size of an object is determined by_ the .size of the angle subtended t ---. at the eye by the object. Con- sider tlie eye to coincide inposition with the lens. Thenin Fig. 432 the angle sub-tended at the eye by the objectPQ is POQ, tliat subtended])y the \a.^e pq\^pOq. Theseangles are identical and atfirst sight we might thinkthere was no magnification. It must be noted, however, that if wewere looking at PQ directly, without using the lens, we would placeit at PQ, at the same distance from 0 as jjq, and the angle thensubtended at the eye is POQ. Hence niacrnification =—S—P 1 _ Il (ai)prox.) = ^.angle POQ PQ ^ ^ ^ PQ Now OPQ and Opq are similar triangles, and OC, OF are perpen-diculars from 0 upon corresponding sides PQ, j^q- Hence ^ = ^^.PQ 00 Again PQ is always placed near the principal focus of the lens,and if y is its focal length, O
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectphysics
