Angle of Refraction
Calculate refraction angle using Snell's law n₁ sin θ₁ = n₂ sin θ₂ with presets for air, water, glass, and diamond. Free online calculator for physics optics.
About This Calculator
The Angle of Refraction Calculator uses Snell's law of refraction (n₁ sin θ₁ = n₂ sin θ₂) to compute how much light bends when passing from one transparent medium to another. This fundamental physics tool is essential for students, engineers, and professionals working in optics, photonics, and optical design.
When light crosses the boundary between two media with different refractive indices, its speed changes, causing the light ray to bend. Snell's law precisely predicts this bending angle. Our calculator includes presets for common media such as air, water, glass, diamond, and more, while also supporting custom refractive indices for specialized applications.
Enter the angle of incidence and select the two media to instantly calculate the angle of refraction. The calculator also detects total internal reflection when applicable and displays the critical angle, helping you understand when light is completely reflected rather than transmitted through the boundary.
Regional Notes
Global: Snell's law and the angle of refraction are universal physics concepts that apply worldwide. The refractive indices of common media are consistent physical constants that do not vary by region. This calculator uses standard reference values for all medium presets.
Frequently Asked Questions
How does the angle of refraction calculator work?
This calculator uses Snell's law of refraction (n₁ sin θ₁ = n₂ sin θ₂) to compute the angle of refraction when light travels from one medium to another. Enter the refractive indices of both media and the angle of incidence to get the refraction angle instantly.
What is Snell's law of refraction?
Snell's law describes how light bends when passing from one medium to another. It states that n₁ sin θ₁ = n₂ sin θ₂, where n₁ and n₂ are the refractive indices of the two media, and θ₁ and θ₂ are the angles of incidence and refraction measured from the normal to the surface.
What is total internal reflection?
Total internal reflection occurs when light travels from a denser medium (higher refractive index) to a rarer medium (lower refractive index) at an angle greater than the critical angle. At this point, all light is reflected back into the first medium and none is transmitted.
What is the critical angle in refraction?
The critical angle is the angle of incidence at which the angle of refraction becomes 90°, meaning the refracted ray travels along the boundary between the two media. It is calculated using θc = arcsin(n₂/n₁) where n₁ > n₂. Beyond this angle, total internal reflection occurs.
What are common refractive indices?
Common refractive indices include: Vacuum 1.0, Air 1.000293, Water at 20°C 1.333, Ethanol 1.361, Ice 1.309, Acrylic 1.49, Window Glass 1.52, and Diamond 2.417. These values represent how much each medium slows light relative to vacuum.
Can I share my angle of refraction calculation results?
Yes, the calculator saves your inputs in the URL so you can bookmark or share the exact calculation with others. Simply copy the URL after calculating to preserve your specific values.
What happens when the angle of incidence is 0°?
When the angle of incidence is 0° (light hits the surface perpendicularly), the angle of refraction is also 0°. The light passes through the boundary without bending, regardless of the refractive indices of the two media.
Is Snell's law valid for all types of waves?
Yes, Snell's law applies to all isotropic materials in all phases of matter for wave propagation, including sound waves and water waves. It is a fundamental principle of wave behavior that depends only on wave speed changes between media.