In Fig.32-30 a light ray in water is incident at angle `theta_(1)` on a boundary with an underlying material into which some of the light refracts . There are two choices of underlying material. For each the angle of refreaction `theta_(2)` versus the incident angle `theta_(1)` is given in Fig. 32-30b . The vertical axis scale is set by `theta_(2s)=90^(@)` . Without calculation determine whether the index of refraction of (a) material 1 and (b) material 2 is greater or less than the index of water (n=1.33) . What is the index of refraction of (c) material 1 and (d) material 2?

Explanation

(a) `n_(2) gt n_(1 )` , (b) the value of `n_(2)` for material 2 is also greater than that oif water `(n_(1))` (c ) `n_(2) ` = 1.4 for material 1 , (d) `n_(2)` = 1.9