a parallel pencil in one direc-tion, the violet rays also as a parallel pencil in another.These rays fall on the object glass of the observing telescope,and are brought to a focus by it; the red rays at one point £,the violet at another V. The spectrum thus formed is viewedby the eye-piece and… … 113. To produce a pure spectrum on a screen. EXPERIMENT (31). Illuminate the slit with a Bunsenflame rendered luminous with sodium chloride. Take a convex 190 LIGHT. [CH. IX lens of about 25 cm. focal length, and place it at about 50 cin.from the slit; an image of the slit will now be formed on…
Heat · Light
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