Exam 22: Reflection and Refraction of Light

A light ray passes from air through a thin plastic slab (n = 1.3)with parallel sides.If the ray in air makes an angle of 45 $\degree$ with the normal after leaving the slab,what is the angle of incidence for the ray in air as it impinges upon the other side of the slab?

A monochromatic light source emits a wavelength of 490 nm in air.When passing through a liquid,the wavelength reduces to 429 nm.What is the liquid's index of refraction?