v 7.9

n = 1 + \frac{N e^{2}}{2 ε_{0} m_{e}} \frac{1}{ω_{0}^{2} - ω^{2}}

${n=1+ \frac{Ne^2}{2\varepsilon_0 m_e} \frac{1}{\omega_0^2- \omega^2}}$

Error