By wave theory the refractive index
Again by Snell's law
This relation suggests that the angle of incidence remaining same angle of refraction decreases with increase of refractive index causing greater deviation or greater bending of ray due to refraction.
This decrease in angle of refraction also indicates that the
When colour X and colour Y are sent through a prism.
If color X bends more than color Y, then the refractive index of the prism for color X is greater than R.I with respect to color Y . And so velocity of X is less than that of Y through the prism. This means Y will travel more rapidly in the prism.