1.
PLEASE EXPLAINED IN GREAT DETAIL
26.31. The drawing shows a crown glass slab with a rectangular cross section. As illustrated, a
laser beam strikes the upper surface at an angle of 60.0°. After reflecting from the upper
surface, the beam reflects from the side and bottom surfaces. (a) If the glass is surrounded by air,
determine where part of the beam first exits the glass, at point A, B, or C (b) Repeat part a,
assuming that the glass is surrounded by water instead of air. a60.01 Crown glass
Solution
refraction index of crown glass=1.52
part a:
at point A:
angle of incidence=60 degrees
let angle of refraction be theta.
then using snell’s law:
1.52*sin(60)=1*sin(theta)
but for this , theta does not exist.
next at point B:
angle of incidence=30 degrees
let angle of refraction be theta.
then using snell’s law:
1.52*sin(30)=1*sin(theta)

2.
==>theta=49.464 degrees
hence here the ray will first exit the glass.
part b:
refractive index of water=1.33
at point A:
let refraction angle be theta.
using snell’s law:
1.52*sin(60)=1.33*sin(theta)
==>theta=81.787 degrees
so if the glass is surrounded by water, the ray will exit at A.