Drude plasma frequency: ω_p = √(n_e·e²/(ε₀·m_e))

The plasma frequency ω_p = √(n_e·e²/(ε₀·m_e)) — the natural collective oscillation frequency of a free-electron gas of density n_e — is the central dispersion-relation parameter in the Drude model of metallic electrodynamics. Physical…