A flat piece of glass covers the top of a vertical cylinder that
is completely filled with water. If a ray of light traveling in the
glass is incident on the interface with the water at an angle
of θa = 36.0 ∘∘ , the ray refracted
into the water makes an angle of 49.4 ∘∘ with the normal
to the interface.
Part A
What is the smallest value of the incident
angle θaθa for which none of the ray refracts into the
water?