Reflection and Refraction

Question

A ray of light is traveling from air to crown glass. The angle that the ray makes with the surface of the glass is 30 degrees. Determine each of the following angles....

a. The angle of incidence

b. The angle of reflection

c. the angle of refraction

d. the angle between the reflected and refracted rays

e. the angle between the incident and refracted rays

f. the angle between the incident and reflected rays

Answer 1

The basics:

First, the angles are measured from the "normal line", which is the line perpendicular to the surface. Thus, in your example, the angle of incidence is 60 degrees.

Reflection is simply the "mirror image"--thus, if the angle of incidence is 60 degrees, the reflected ray will have an angle relative to the normal of -60 degrees.

For refraction, use Snell's law:

v is the velocity, and n is the refractive index. Look up the index of crown glass using Google.

In the equation, call theta-1 the incoming ray, It is in air, so n(1) =1

Simplifying and rearranging the equation, we get:

sin (theta-2) = sin(60) / n(2)

And then:

theta-2 = arcsin ( sin(60) / n(2) )

More here: https://en.wikipedia.org/wiki/Refraction