Refraction

Snell’s law

An interactive lesson with 8 steps, about 7 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Refractive index $n = c/v$: light is slower in denser materials.
• Snell's law: $n_1\sin\theta_1 = n_2\sin\theta_2$.
• Entering a denser material, light bends toward the normal. Leaving it, light bends away.

Steps

1. Bent straw
2. Into the glass
3. Snell’s law
4. Why light bends
5. The quickest path
6. Into water
7. Speed in glass
8. Spear fishing