A container of flint glass (n = 1.66)holds a small quantity of benzene (n = 1.501).What is the critical angle for internal reflection of a ray in the glass when it is incident on the glass-to-liquid surface?
A)89.5 $\degree$
B)64.7 $\degree$
C)41.1 $\degree$
D)37.0 $\degree$

Question

Quizplus · Accepted Answer

Using Snell's law at the glass-to-liquid interface, we have:
n1*sin(theta1) = n2*sin(theta2)
where n1 is the index of refraction of glass (1.66), n2 is the index of refraction of benzene (1.501), theta1 is the incident angle, and theta2 is the refracted angle.
For the critical angle, we have theta2 = 90 degrees, which means sin(theta2) = 1. Substituting into Snell's law and solving for theta1, we get:
sin(theta1) = n2/n1
sin(theta1) = 1.501/1.66
theta1 = sin^-1(1.501/1.66) = 64.7 degrees
Therefore, the critical angle is 64.7 degrees, which is choice B.

A Container of Flint Glass (N = 1 °\degree° B)647 °\degree° C)411 °\degree°

A Container of Flint Glass (N = 1 $\degree$ B)647 $\degree$ C)411 $\degree$