 ##  [Refractive Index](/refractive-index) 

  ##  [Refractive Index](https://natural.quantumdictionary.io/refractive-index-0) 

  
 [![Natural & Formal Sciences Dictionary](/sites/default/files/styles/large/public/2026-01/Natural%20%26%20Formal%20Sciences.png.webp?itok=2kCDRVQv)](/topic-specific-dictionaries/natural-formal-sciences)


**Natural &amp; Formal Sciences Dictionary**

 
Definition

Dimensionless ratio n describing the phase velocity of light in a medium relative to vacuum (n = c/v), which determines the angle of refraction at interfaces via Snell's law and influences optical propagation.

 
 ##  [Refractive Index](https://humanitites.quantumdictionary.io/refractive-index-1) 

  
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**Humanities &amp; Arts Dictionary**

 
Definition

Dimensionless ratio n = c/v that compares the speed of light in vacuum (c) to its phase velocity v in a material at a specified wavelength and temperature; equivalently the parameter appearing in Snell's law that governs refraction at interfaces.