Refraction

This lesson covers: 

  1. What refraction is
  2. How light changes direction during refraction

Light changes direction as it moves between materials

Diagram showing light refraction as an incident ray passes from air to glass and changes direction to become a refracted ray.

Light travels through transparent materials that allow it to pass through, known as media.

When light crosses between two different transparent media, such as from air to glass, the light rays change direction, or refract.

How light changes direction during refraction

Diagram showing how light changes direction during refraction when moving between less dense and more dense media.

There are two key rules for understanding how light changes direction when moving between media.

  1. Less dense to more dense medium - Light moves towards the normal line when going from a less dense medium like air to a more dense medium like glass.
  2. More dense to less dense medium - Light moves away from the normal line when going from a more dense medium like glass to a less dense medium like air.