Question

Suppose a beam of white light is incident at a 41° angle upon a glass plate 65 cm thick. The index of refraction of the glass for blue light is 1.65, and for red light it is 1.60 (see figure below). Determine the distance between the blue light and red light as they exit the glass plate

Answer 1

Use Snell's Law:
\[n_{i}\sin(\theta _i)=n_{t}\sin(\theta _t)\]
You are given ni and theta i.
For red light, you would use nt=1.60 and for blue light you would use nt=1.65
You will solve for theta t.

This is the angle that the light will be traveling along once inside the glass.

Then using some basic trigonometry as shown in the picture below, you can find the distance the light will deviate from the normal.


By solving for 'd' for each of the two colors of light, you can subtract them to find the distance between the colors of light.