Hawkins electrical guide ... : questions, answers & illustrations : a progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications ; a practical treatise (1914)
Hawkins, N. (Nehemiah), 1833-1928 · New York : T. Audel & Co. · leaf 30
hich the speed is greater. Ques. How do external objects appear to an eye underwater? 2,684 HAWKINS ELECTRICITY Ans. They appear to lie within a cone whose angle is 97explained in fig. 3,777. as Lenses,—A lens may be defined as, a piece of glass or othertransparent substance with one or both sides… … •<br5iV>o< ••>••* Fig. 3,777.—Appearance of external objects to an eye under water. Since the critical anglefor water is 48^°, an eye located at M will see objects above the water as though locatedwithin a cone whose angle is 2X48^° = 97*. The reason for this is because if the eyelook…
Electrical engineering
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