Dispersion is the splitting of white light into its constituent colors.

• This happens because the speed of light in a medium (and thus the refractive index $n$) depends on the wavelength (colors).
• According to Cauchy's formula: $n(\lambda )=A+\frac{B}{{\lambda }^2}+...$
• Shorter wavelengths (Violet) experience a higher refractive index and bend more than longer wavelengths (Red).