One Shot|Refraction of light

Reflection of light and Refraction of light .

What is refraction of light? How is refractive index of material related to velocity of light?

Refraction Of Light|The Refractive Index|Refraction BY Spherical Lenses

When a ray of light is incident normally on one refracting surface of an equilateral prism (Refractive index of the material of the prism =1.5