gcsescience.com                                       30                                       gcsescience.com


What is the Critical Angle and Total Internal Reflection?

1.  When a light ray emerges from glass into air,
it is refracted and bends away from the normal, so i < r.

Refraction of Light from Air to Glass

2.  As i is made bigger, the refracted ray
gets closer and closer to the surface of the glass.
When i equals the critical angle, the refracted ray
is just touching the glass surface.

Critical Angle

The critical angle is different for different materials.
For glass it is about 42 degrees.

Total internal reflection happens when
i is bigger than the critical angle (see the next page).

back      Links      Waves      Light      Revision Questions      next

gcsescience.com       Physics Quiz       Index       Light Quiz       gcsescience.com

Home      GCSE Chemistry      GCSE Physics

Copyright © 2015 gcsescience.com. All Rights Reserved.