Snell's Law Refraction Calculator
Angle of refraction between two media, the critical angle and the speed of light in each.
Results
Angle of refraction
22.0301
°
Critical angle
0.0000
°
Speed
299,792,458
m/s
Speed
224,900,569
m/s
What this tool does
Light bends because it travels at different speeds in different materials: about 1.000 in air, 1.333 in water, 1.5 in ordinary glass and 2.42 in diamond. When light leaves a denser medium at a steep enough angle it stops leaving altogether — the critical angle is where total internal reflection begins, and it is what makes optical fibre work.
Formula
n₁ sin θ₁ = n₂ sin θ₂
Variables
| Symbol | Meaning | Unit |
|---|---|---|
n1 | Refractive index (first medium) | — |
n2 | Refractive index (second medium) | — |
a1 | Angle of incidence | ° |
A2 | Angle of refraction | ° |
CA | Critical angle | ° |
V1 | Speed | m/s |
V2 | Speed | m/s |
Worked example
- Refractive index (first medium)1
- Refractive index (second medium)1.333
- Angle of incidence30 °
- Angle of refraction22.0301 °
- Critical angle0.0000 °
- Speed299,792,458 m/s
- Speed224,900,569 m/s
Limitations
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.