Snell's Law Calculator: Refraction Angle, Refractive Index and Critical Angle

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Choose which quantity you want to calculate; fill in the other three.
Angle between the incoming ray and the normal to the surface, 0-90 degrees.
°
Angle of refraction (θ₂)Moderate refraction
22.037°

The angle the refracted ray makes with the normal in medium 2.

Angle of incidence (θ₁)30°
Refractive index n₁1.0003
Refractive index n₂1.333
Speed ratio (v₂ / v₁)0.7504
Wavelength ratio (λ₂ / λ₁)0.7504
Total internal reflectionNo total internal reflection
n₁ (medium 1)1.0003
n₂ (medium 2)1.333

The refracted ray exits at 22.037 degrees.

  • Light bends toward the normal because medium 2 is optically denser than medium 1.
  • Light travels 25.0% slower in medium 2 than in medium 1.
  • No critical angle exists because light is travelling from the less dense to the denser medium, so total internal reflection cannot occur.

Next stepTry switching media or adjusting the incident angle to see how refraction changes.

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