Solve the problem.When light travels from one medium to another-from air to water, for instance-it changes direction. (This is why a pencil, partially submerged in water, looks as though it is bent.) The angle of incidence ?i is the angle in the first medium; the angle of refraction ?r is the second medium. (See illustration.) Each medium has an index of refraction-ni and nr, respectively-which can be found in tables. Snell's law relates these quantities in the formula ni sin?i = nr sin ?rSolving for ?r, we obtain ?r = sin-1 Find ?r for fused quartz (ni = 1.46), ethyl alcohol (nr = 1.36), and ?i = 8.5°. 

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What will be an ideal response?

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?r = 9.13°

Mathematics