11.9 Total Internal Refraction

Question 1

When does total internal refraction occur?

Answer 1

It occurs at the boundary between two different media. When the light strikes the boundary at a large angle to the normal, it is totally internally reflected. All the light is reflected back into the original medium. There is no light energy refracted out of the original medium.

Question 2

The conditions for total internal refraction.

Answer 2

1) The light must be travelling through a medium with a higher refractive index as it strikes the boundary with a medium with a lower refractive index. For example: when light in glass meets air, but not

2) The angle at which the light strikes the boundary must be above the critical angle. This angle depends on the refractive index of the medium.