Refraction of light:
Refraction of light is the phenomenon in which light waves change direction as they pass from one medium to another. This change in direction is due to the change in the speed of light as it travels through different mediums. When light passes from a rarer medium (like air) to a denser medium (like water or glass), it tends to slow down, causing the light waves to bend towards the normal. Conversely, when light passes from a denser medium to a rarer medium, it speeds up, and the light waves bend away from the normal.

Refractive index:
The refractive index is a measure of how much a medium can bend or refract light. It is denoted by the symbol 'n' and is the ratio of the speed of light in a vacuum to the speed of light in the medium. Mathematically, it can be represented as:

Refractive index (n) = speed of light in vacuum / speed of light in the medium

The refractive index of a medium determines the extent to which light is bent when it enters or exits the medium. It is a fundamental property of different materials and plays a crucial role in various optical phenomena.

Key Points:
- Refraction of light is the bending of light waves as they pass from one medium to another.
- It occurs due to the change in the speed of light in different mediums.
- When light enters a denser medium, it slows down and bends towards the normal.
- When light enters a rarer medium, it speeds up and bends away from the normal.
- The refractive index is a measure of how much a medium can refract light.
- It is the ratio of the speed of light in a vacuum to the speed of light in the medium.
- The refractive index determines the extent of bending of light in a medium.
- Different materials have different refractive indices, which affect the behavior of light in those materials.
- The refractive index is a crucial parameter in optics and has applications in lens design, fiber optics, and many other fields.

Light travels faster in a vacuum than it does in any other medium. Light changes speed as it passes from one medium to another. This is called refraction. ... The refractive index of a material is a measure of the change in the speed of light as it passes from a vacuum (or air as an approximation) into the material.