Introductory course of natural philosophy for the use of schools and academies. Ed. from Ganot's popular physics. By William G. Peck (1869)
Ganot, Adolphe, 1804-1887, Peck, William Guy, 1820-1892 · New York A.S. Barnes · leaf 281
e distancefrom the mirror, the rays will be parallel, and the corre-sponding focus is at F, the principal focus. (See Fig. 162.) If the radiant approaches the mirror, the focus recedesfrom it. If the radiant is beyond the optical centre, (7, the focusis between i^and C. If the radiant is at C, the… … Fig. 165. If the radiant is between F and A, as shown in Fig. 165,the rays arc reflected so as to diverge, and on being pro-duced backwards, meet at p. In this case the focus isbehind the mirror, and is said to be virtual (Art. 273). if the radiant is not on the axis, the pencil of rays is…
Physics
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