Reflection at normal incidence consider an electromagnetic wave in vacuum, with field components of the form let the wave be incident upon a medium of dielectric constant E and permeability ? = 1 that fills the half-space x > 0. Show that the reflectivity coefficient r(w) as defined by E(refl) ? r(w) E (inc) is given by where n + iK = ?^1/2, with n and K real. Show further that the reflectance is

E,(inc) B.(inc) = Aex-) n+iK - 1 n + K +1 r(w) R(w) (n-1)2 + K (n+1) + K