The Cauchy’s dispersion formula is?

Cauchy's dispersion formula relates the refractive index of a material to the wavelength of light. It is commonly used to describe the dispersion (variation of refractive index with wavelength) in transparent materials.

The formula is:

n(λ) = A + B/(λ² - C)

Where:

n(λ) is the refractive index at wavelength λ
A, B, and C are constants specific to the material
λ is the wavelength of light (in micrometers)
This formula approximates the refractive index of a material as a function of the wavelength of light passing through it. It is often used in the study of optical properties of glasses and other transparent materials.

In this equation:

A represents the refractive index at an infinite wavelength.
B and C are parameters that depend on the specific material, and they help describe how the refractive index changes with wavelength.
This formula is mainly applicable in the visible range of the spectrum, though it can also be extended to other regions with appropriate adjustments for the constants.