Question

How does the speed of light change when it passes from glass to water? 

Answer 1

Refractive index of water, μ w = 1.33
Refractive index of air, μ a = 1.0003
Refractive index of glass, μ g = 1.5
This implies that μ a < μ w < μ g
The speed of light decreases when it enters from a rarer medium to denser medium and increases when it enters from a denser medium to rarer medium.
Therefore, the speed of light increases when light ray passes from water to air and the speed of light decreases when light ray passes from water to glass.