Cold sodium atoms (near absolute zero) in a state called a Bose-Einstein condensate can slow the speed of light from its normally high value to a speed approaching that of an automobile in a city. The speed of light in one such medium was recorded as 60.15 km/hr.
(a) Find the index of refraction of this medium.
(b) What is the critical angle for total internal reflection if the condensate is surrounded by vacuum?