Homework Statement
Derive the Sellmeier equation
n^{2} = 1 + \frac{A\lambda^{2}_{vac}}{\lambda^{2}_{vac}-\lambda^{2}_{0,vac}}
from
(n+i\kappa)^{2}= 1 + \frac{\omega^{2}_{p}}{\omega^{2}_{0}-
i\omega\gamma - \omega^{2}}
for a gas or glass with negligible absorption (i.e. \gamma ≈ 0...