A light source is at the bottom of a pool of water (the index of refraction of water is 1.33). At what minimum angle of incidence will a ray be totally reflected at the surface?
B. 25o
C. 50o
D. 75o
E. 90o
(GR9677 #56)
Snell's Law: nw sin θi = na sin θr
For total internal reflection, θr = 90o
nw sin θi = na
sin θi = na/nw = 1/1.33 ≈ 3/4
Convert to degree, θ = ¾ × 180/π ≈ 45o closer to 50o
Answer: C
nw sin θi = na
sin θi = na/nw = 1/1.33 ≈ 3/4
Convert to degree, θ = ¾ × 180/π ≈ 45o closer to 50o
Answer: C
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