# Thread: Index of refraction problem

1. ## Index of refraction problem

A beam of light with red and blue components of wavelengths 670 nm and 425 nm, respectively, strikes a slab of fused quartz at an incident angle of 30o. On refraction, the different components are separated by an angle of 1.31 X 10-3 rad. If the index of refraction of the red light is 1.4925, what is the index of refraction of the blue light?

2. Originally Posted by chicagomike
A beam of light with red and blue components of wavelengths 670 nm and 425 nm, respectively, strikes a slab of fused quartz at an incident angle of 30o. On refraction, the different components are separated by an angle of 1.31 X 10-3 rad. If the index of refraction of the red light is 1.4925, what is the index of refraction of the blue light?
Outline:

Step 1) Compute the refracted angle using snells law for red light.
Step 2) Now subtract 1.31 X 10-3 rad from the refracted angle of red light to get blue lights refracted angle.
Step 3) Finally substitute this angle again in Snells law to obtain ref.index of blue light

So the Physics part of it:
Why did I subtract the angle?