💡 n = refractive index (no units) | θ = angle in degrees | Air n≈1.00 | Water n≈1.33 | Glass n≈1.52 | Diamond n≈2.42
📖 How to Use This Refractive Index Calculator
1
Select what to calculate - Choose n₂, n₁, θ₁ (incidence), or θ₂ (refraction).
2
Enter known values - Input the known refractive indices and angles.
3
Click "Calculate" - Get the result with step-by-step solution using Snell's law.
🔆 Understanding Snell's Law
Snell's Law describes how light bends (refracts) when passing from one medium to another. The formula is n₁ sinθ₁ = n₂ sinθ₂, where n is the refractive index and θ is the angle measured from the normal (perpendicular) to the surface.
The refractive index of a medium indicates how much light slows down in that medium compared to vacuum. Higher refractive index means light travels slower and bends more toward the normal.
Lenses (Eyeglasses, Cameras): Refractive indices determine lens power
Fiber Optics: Total internal reflection in optical fibers (n_core > n_cladding)
Prisms: Dispersion separates white light into colors
Mirage: Bending of light due to temperature gradients in air
Rainbows: Refraction and reflection in water droplets
Underwater vision: Objects appear closer due to refraction
❓ Frequently Asked Questions (FAQ)
What is total internal reflection?
Total internal reflection occurs when light tries to go from a higher refractive index medium to a lower index medium at an angle greater than the critical angle. All light is reflected back, none is transmitted.
What is the critical angle?
The critical angle is the angle of incidence in the higher-index medium that produces a 90° refraction angle. It's given by θ_c = arcsin(n₂/n₁). Beyond this angle, total internal reflection occurs.
Why does a straw look bent in water?
Light from the straw refracts (bends) as it exits water into air. Your brain interprets this as a bent straw because light appears to travel in straight lines.
How does refractive index depend on wavelength?
Refractive index decreases with increasing wavelength (normal dispersion). This causes dispersion - different colors bend differently, creating rainbows and spectra.
Can refractive index be less than 1?
For most materials, n > 1. Metamaterials can achieve n < 1 for specific wavelengths, but this is an advanced research area. Vacuum has n = 1, the minimum for normal materials.
What happens when light enters a medium with higher refractive index?
Light bends toward the normal (angle decreases), slows down, and wavelength decreases. Frequency remains constant.