Dispersion

Smaller wavelength light gets refracted more in prisms. Basically, light shone through a prism “disperses”
3b1b Video Explaining Dispersion on an atomic level with simple harmonic oscillator

$n=\frac{ck}{\omega }\cong \frac{N{q}^2}{2m{\epsilon }_0}\sum _j\frac{f_j({\omega }_j^2-{\omega }^2)}{({\omega }_j^2-{\omega }^2{)}^2+{\gamma }_j^2{\omega }^2}$

• Index of refraction for a medium undergoing disperision

$n=1+A\left(1+\frac{B}{{\lambda }^2}\right)$