I don't understand it at all. I'm in regular High school physics, so If you can explain it that'd be great.

A scuba diver uses a waterproof flashlight to shine a ray of light so it strikes the surface of the water at an angle of incidence. Use Snell's law to fin the angle of incidence that would give and angle of refraction for the refracted ray to be directed right along the surface, and show that the angle of incidence is the same as the critical angle for total internal reflection.

No numbers, so, no clue... lol

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