(a) Find the critical angle of total internal reflection from glass with refraction index n = 1.51 into air.
?cr = ___°
(b) An optic fiber is made from two glass shells with the refraction indices n1 = 1.46 (internal shell) and n2 = 1.27 (external shell). Find the critical angle of total internal reflection of light rays travelling from the inner to outer shell.
?cr = ____°
(c) A glass plate has the critical angle of total internal reflection ?air = 46.5 ° in air. Find the critical angle for the same plate suspended in water (refraction index of water is n = 1.333).
?water = ____°