Question

In going from water to glass will speed of light increase or decrease explain

Answer 1

We know the fact that light travel faster in optically rarer medium as compared to optically denser medium and it is obvious to know that water is rarer than glass.

Answer 2

On going from water to glass, the speed of light will decrease as the refractive index of glass(1.5) is more than water (1.33). Glass is denser than water.