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Calcimator

Snell's Law Calculator

Calculate the refraction angle when light passes between two media using Snell's law: n₁ sin(θ₁) = n₂ sin(θ₂). Includes critical angle and Fresnel reflectance.

Inputs

°

Results

Refraction Angle

48.59

Critical Angle41.81
Reflectance0.06
Transmittance0.94
How to Use This Calculator
  1. Enter Refractive Index n₁, Incident Angle, and Refractive Index n₂.
  2. Review the Refraction Angle result.
  3. Use Critical Angle and Reflectance to inform your decision.
  4. Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Refractive Index n₂

Refractive Index n₂Refraction Angle
1.432.39
2.418.21
3.612.03
4.69.38

What each input means

Refractive Index n₁
Refractive index of the first medium. Glass ≈ 1.5, water ≈ 1.33, diamond ≈ 2.42.
Incident Angle
Angle of the incident ray measured from the surface normal.
Refractive Index n₂
Refractive index of the second medium. Air ≈ 1.0003, vacuum = 1.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Refractive Index n₁ = 1.5, Incident Angle = 30, Refractive Index n₂ = 1 = 3 input(s) provided
  2. Calculate Refraction Angle
    48.59 = 48.59
  3. Calculate Critical Angle
    41.81 = 41.81
  4. Calculate Reflectance
    Reflectance
    0.0552 = 0.0552

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