ABAC Right Triangular Glass Prism and A Light Ray Question

Description

B:02
B
2. (25 pts) A light ray enters a right
triangular glass prism normally from
the left edge as shown. The prism
has an index of refraction of n=1.67
. Assume air is outside of the glass
prism.
n
i. What is the critical value dc
for the angle ø so that the
refracting ray exiting the
right face of the prism at point A will be barely skimming along the right face of the prism,
i.e. 04 = 90°?
ii. To completely eliminate the refracted ray from the right face (Total Internal Reflection at
point A), should one choose a right triangular prism with p larger or smaller the critical
angle de calculated in part i ?
iii. Now consider a reflected ray from point A. It will reach the base of the prism at point B.
What is the critical value for the angle o so that the refracting ray exiting the base of
the prism at point B will be barely skimming along the bottom of the prism, i.e. 0g = 90° ?
[Note: the condition for part iii is different from part i.]