Refraction / Total Internal Reflection

Refraction is when light bends when going through a more or less dense medium

The normal line is at 90 degrees to the side of the glass block (Perpendicular)

When a light enters a more dense medium the light refracts

When the light enters a more dense medium, the light bends towards the normal

When the light enters a less dense medium, the light bends away from the normal

When a light enters a less dense medium the light does not refract

The normal line is the boundary between air and the solid glass

Air particles are apart so it is less dense

Glass particles are very close and are more dense

…