Snell's Law
Part of the Optics, Waves and Modern Physics section of Coddy's Physics journey. Lesson 3 of 53.
Snell's law, both angles from the normal:
n₁ sin θ₁ = n₂ sin θ₂
Air into glass at 40°: sin θ₂ = sin 40° / 1.5 = 0.4285, so θ₂ = 25.4°.
The bigger n, the closer the ray to the normal. Use sin⁻¹ to get an angle back from its sine.
Challenge
A ray of light in air (n₁ = 1) reaches glass (n₂ = 1.5) at 40° from the normal. What is the angle of refraction θ₂?
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