Total Internal Reflection
Part of the Optics, Waves and Modern Physics section of Coddy's Physics journey. Lesson 4 of 53.
From glass into air, light bends away from the normal. At the critical angle the refracted ray runs along the surface:
sin θc = n₂ / n₁
Glass into air: θc = 41.8°. Past it, all the light reflects back.
Only from a bigger index into a smaller one. Fibres and diamonds use it.
Challenge
What is the critical angle θc for light going from glass (n₁ = 1.5) into air (n₂ = 1)?
Try it yourself
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Optics, Waves and Modern Physics
1Reflection and Refraction
Reflection of LightThe Refractive IndexSnell's LawTotal Internal ReflectionDispersionApparent DepthRecap - Optical Fiber4Mechanical Waves
What a Wave IsTwo Graphs of a WaveWhen Pulses MeetInterferenceStanding WavesHarmonicsRecap - Guitar String