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

1.3324
Dimensionless

n = c / v

Light Speed in Medium

km/s:225407.86
m/s:225407863
% of c:75.2%

Optical Properties

412.8 nm
Wavelength in medium
(550nm green light)
300 km/s
Speed in vacuum
(constant c)
24.8%
Speed reduction
compared to vacuum

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

This material has a refractive index of 1.3324, meaning light travels at 75.2% of its vacuum speed.
💧 Medium refractive index - typical of liquids and common glass.

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

Vacuum:1.000
Air (STP):1.000293
Water (20°C):1.333
Ice:1.31
Crown Glass:1.52
Flint Glass:1.61
Diamond:2.419

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.