折射率n = sin45˚/sin30˚ = 0.707/0.5 = 1.41临界角α, n = 1/sinαsinα = 1/n = 0.707α = 45˚
折射率n=sin45/sin30=[(根号2)/2]/(1/2)=根号2=1.4142sinA=1/n=1/(根号2)=(根号2)/2临界角A=45度
