Light in air is initially traveling parallel to the face AC of an equilateral triangular prism,as shown in the figure.The prism is made of glass with an index of refraction of 1.52.If the light does not strike the face AC,what is the angle between the ray as it leaves the prism at face BC and the normal in air at that face?
A) 83°
B) 19°
C) 59°
D) 27°
E) 55°

Question

Light in air is initially traveling parallel to the face AC of an equilateral triangular prism,as shown in the figure.The prism is made of glass with an index of refraction of 1.52.If the light does not strike the face AC,what is the angle between the ray as it leaves the prism at face BC and the normal in air at that face? 
A) 83° 
B) 19° 
C) 59° 
D) 27° 
E) 55°

Quizplus · Accepted Answer

Since the prism is equilateral, the incident angle on face AB is 60°. Using Snell's Law, we can find the angle at which the light bends as it enters the glass:

sin(60°)/1 = sin(theta)/1.52
theta ≈ 39.3°

Now, as the light travels through the prism, it will strike face BC at an angle of 90° - 39.3° = 50.7°. Using Snell's Law again, we can find the angle at which the light bends as it exits the glass prism into air:

sin(theta)/1.52 = sin(phi)/1
phi ≈ 83°

Therefore, the angle between the ray as it leaves the prism at face BC and the normal in air at that face is 90° - 83° = 7°. However, the question asks for the angle between the ray and the normal, not the angle between the ray and the surface. Since the surface is perpendicular to the normal, the answer is 90° - 83° = 7°.

Light in Air Is Initially Traveling Parallel to the Face