Refractive Index

n = \frac{c}{v}

The refractive index is the ratio of the speed of light in vacuum to its speed in the medium.

Variables

Refractive index

Allowed values: 1 or more

unitless

Speed of light in vacuum

Allowed values: greater than 0

m/s

Speed of light in medium

Allowed values: greater than 0

m/s

Your notes

0/5000

Constants in this formula

Speed of Light in Vacuum

299,792,458. Exact by definition.

m/s

Other optics formulas with the same quantities

Apparent Depth (Refraction) shares Refractive index
Optical Path Length (Wave Optics) shares Refractive index
Prism Minimum Deviation (Prisms) shares Refractive index

Where this formula is listed

Optics formulas, under Refraction, alongside Critical Angle.
In the optics list it comes after Snell's Law and before Critical Angle.
Optics formula sheet, one of 34 formulas printed with symbol keys and SI units.
The full formula index, grouped by category and topic.

Common questions

What is the Refractive Index formula?

Refractive Index is written n = c/v. The refractive index is the ratio of the speed of light in vacuum to its speed in the medium. It belongs to Optics, under Refraction.

What are the units in n = c/v?

In SI units, n is refractive index (dimensionless); c is speed of light in vacuum, measured in m/s; v is speed of light in medium, measured in m/s.