Physics and Engineering
Snell's Law Calculator
Snell's Law Calculator calculate a refracted angle, critical angle, and refraction status from two refractive indices and an incident angle.
Physics and Engineering
Snell's Law Calculator
Calculate a refracted angle, critical angle, and refraction status from two refractive indices and an incident angle.
Formula
n1 x sin(incident angle) = n2 x sin(refracted angle).
About the Snell's Law Calculator
Calculate a refracted angle, critical angle, and refraction status from two refractive indices and an incident angle.
How the Snell's Law Calculator Works
The transmitted sine is solved from the index ratio; values above one are reported as total internal reflection instead of forcing an invalid inverse sine.
Formula
n1 x sin(incident angle) = n2 x sin(refracted angle).
The calculation runs in your browser. Values are validated for required ranges, compatible units, and method-specific restrictions before results are displayed.
Required Inputs
- Incident-medium refractive index (required).
- Transmitted-medium refractive index (required).
- Incident angle from normal (required) - enter in degrees.
Results Reported
The result panel reports the final answer and the intermediate quantities needed to check the calculation:
- Refraction status
- Refracted angle (degrees)
- Critical angle when applicable (degrees)
- Calculated sine of refracted angle
Snell's Law Calculator Example
Select Example Data in the calculator to load this reproducible input set:
| Input | Example value |
|---|---|
| Incident-medium refractive index | 1.5 |
| Transmitted-medium refractive index | 1 |
| Incident angle from normal | 30 degrees |
How to Use the Calculator
- Confirm that the calculator title and formula match the quantity you need.
- Enter every required value using the unit shown with its field.
- Select Example Data to inspect a valid input set, or enter your own values and select Calculate.
- Review all reported values and the displayed formula before using the answer.
- Use Copy Result or Download CSV when you need a reusable record.
Accuracy and Limitations
Angles are measured from the surface normal. Indices may depend on wavelength, temperature, and material, and this geometric-optics model ignores absorption and scattering.
Keep units consistent, use measurements that represent the actual situation, retain full precision during the calculation, and round only the final answer. Professional decisions may require current official rules, field measurements, laboratory methods, or specialist review.
Frequently Asked Questions
What does the Snell's Law Calculator calculate?
Calculate a refracted angle, critical angle, and refraction status from two refractive indices and an incident angle.
Which formula does the Snell's Law Calculator use?
n1 x sin(incident angle) = n2 x sin(refracted angle). The transmitted sine is solved from the index ratio; values above one are reported as total internal reflection instead of forcing an invalid inverse sine.
What should I check before using the Snell's Law Calculator result?
Angles are measured from the surface normal. Indices may depend on wavelength, temperature, and material, and this geometric-optics model ignores absorption and scattering.