Loi de Snell

How to use it

1. N₁ = 1.0 (air), θ₁ = 45°, nâ‚‚ = 1.5 (glass)
2. Calculate sans(45°) ≈ 0.7071
3. Apply Snell's law: sans(θ₂) = (1.0 × 0.7071) ÷ 1.5 = 0.4714
4. Find θ₂ = arcsin(0.4714) ≈ 28.1255°

Common mistakes

• ⚠️ Using degrees in sine function without radian conversion
• ⚠️ Not checking for Total internal reflection condition
• ⚠️ Swapping n1 and n2 in the formule

Worked example

Find the refraction angle when light enters glass (n=1.5) from air at 45°.

The refraction angle {theta2} degrees is the angle of the light ray in the second medium.

Input guide