Newall, H. F · London : Society for Promoting Christian Knowledge · leaf 41
that the beam between them is parallel, *. e. consistsof parallel rays (see Fig. 20). The lens nearestto the slit is chosen and placed in such a mannerthat the divergent rays emanating from the slitare rendered parallel in consequence of passingthrough the lens. The lens is called the… … Fig. 20. parallel beam through the prism and emerge fromit still a parallel beam; rays of any other colour,whilst remaining parallel amongst themselves, passin a slightly different direction and emerge from theprism parallel to one another, but slightly inclinedto the rays of the first colour. Each…
Spectroscope · Spectrum analysis
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