Refractive Index of B with respect to A
The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, for the light of a given colour and for the given pair of media. This law is also known as Snell’s law of refraction of light. The law follows from the boundary condition that a wave is continuous across a boundary, which requires that the phase of the wave be constant on any given plane.
n = sin 60/sin 45
n = (√3 /2) /(1/√2)
n = √3/√2