∂/∂x = iA, ∂/∂t = -iAv, ∂/∂y = ∂/∂z = 0, uy = uz = 0
Then ∂D_y/∂t = -c∂Hz/∂x - u∂Dy/∂z ... (1·21)
and ∂Bz/∂t = -c∂Ey/∂x - u∂Bz/∂x (2·21)
Since D = KE and B = μH, we have
iAv(κEy) = -ciA(Hz + uKEy) (1·22)
iAv(μHz) = -ciA(Ey + uμHz) (2·22)
or v(K - u)Ey = cHz (1·23)
μ(v - u)Hz = cEy (2·23)
Multiplying (1·23) by (2·23)
μK(v - u)² = c²