A very narrow beam of white light is incident at 47.50° onto the top surface of a rectangular block of flint glass 13.6 cm thick. The indices of refraction of the glass for red and violet light are 1.649 and 1.678, respectively.

1. Calculate dispersion angle...Figured this out already.

2. How wide is the beam when it reaches the bottom of the block, as measured along the bottom surface of the block?

3. When the rainbow-colored beam emerges from the bottom of the block, the exiting rays of light are once again parallel. Calculate the distance between the exiting red and violet rays (i.e., the thickness of the rainbow).

Any help with 2 and 3 would greatly be appreciated.
Thanks

1 answer

2. you know the dispersion angle. YOu will have to use trig to find width at trig bottom. Draw the figure, label the paths, and I assume you know how thick the glass is.
3. Same principle as 2.