ter. Thisfollows from the fact mentioned above, that when a sphericalwavefront is refracted at a spherical surface, it emerges nottruly spherical. Figure 52 illustrates this defect in an exag-gerated manner. The rays are drawn, but not the wravefronts. 92 LIGHT 0 is a point source, from which all… … Figure 52 is very nearly spherical, these rays will all intersect nearly ata single point f. Rays 4 and 5, however, cross before reachingf, at such a point as e, and the corresponding rays 7 and 8 ate. Rays 3 and 4 will cross still nearer the lens, as at c, 3and 2 at b, 2 and 1 at a, etc.…
Light
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