Index of Refraction Calculator
Calculate refractive index and light speed in different media using Snell's law principles
Calculate Index of Refraction
Speed → Index
Calculate refractive index from light speed
Index → Speed
Calculate light speed from refractive index
Speed of light in the material (slower than in vacuum)
Refraction Results
Refractive Index
n = c / v
Light Speed in Medium
Optical Properties
Formula: n = c / v, where c = 299,792.458 km/s
Physical meaning: Light travels 1.33× slower in this medium than in vacuum
Material Analysis
Example Calculation
Water at 20°C
Given: Light travels at 225,000 km/s in water
Speed of light in vacuum: c = 299,792.458 km/s
Refractive index: n = c / v = 299,792.458 / 225,000 = 1.333
Wavelength change: 550nm → 413nm (green light)
Physical Interpretation
• Light slows down by 25% when entering water from air
• Wavelength decreases proportionally to maintain frequency
• This causes the bending of light (refraction) at interfaces
• Higher refractive index = greater light bending
Common Materials
Refraction Facts
Refractive index is always ≥ 1 (nothing travels faster than light in vacuum)
Higher index = more light bending at interfaces
Temperature affects refractive index of liquids
Wavelength changes, but frequency remains constant
Essential for lens design and optical instruments
Understanding Index of Refraction
What is Refractive Index?
The refractive index (or index of refraction) describes how light propagates through a material. It's a dimensionless quantity that determines how much light bends when entering a different medium and indicates how much the speed of light is reduced inside the material.
Physical Significance
- •Determines the amount of light bending at interfaces
- •Affects wavelength while preserving frequency
- •Critical for optical design and lens systems
- •Varies with temperature and wavelength
Mathematical Formula
n = c / v
- n: Refractive index (dimensionless)
- c: Speed of light in vacuum (299,792,458 m/s)
- v: Speed of light in the medium (m/s)
Key Insight: Since light cannot travel faster than c (speed of light in vacuum), the refractive index is always ≥ 1, with n = 1 only for vacuum.
Applications and Uses
Optics & Lenses
Essential for designing cameras, microscopes, telescopes, and eyeglasses. Different refractive indices enable focusing and magnification.
Fiber Optics
Total internal reflection depends on refractive index differences, enabling efficient light transmission in optical fibers.
Material Analysis
Used to identify substances, measure purity, and determine concentration in solutions using refractometry techniques.