Laurence, Lionel · London, School of Optics · leaf 224
viewed,and a reading is taken on the circle. The prism is then placed in position,and the telescope must be rotated to T until the image of the slit can againbe seen. The angular distance through which T is moved is the deviatingangle of the prism, care being taken that the deviation is a minimum.… … Fjg. 224. Fig. 225. The principal angle of a prism is measured by turning the prism until itsedge splits into two halves the beam of light issuing from the collimator(Fig. 225). The telescope is rotated to T until the image of the slit is seenreflected from the one surface, and then turned to T to…
Optics
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