Putting B = μ H and D = ϵ E ‍, ‍ as above, we can eliminate B and D to obtain equations in only E and H : ω ω μ μ H = k × × E ω ω ϵ ϵ E = − − k × × H . If the material parameters ϵ and μ are real (as in a lossless dielectric), these equations show that k , E , H form a right-handed orthogonal triad, so that the same equations apply to the magnitudes of the respective vectors. Taking the magnitude equations and substituting from (2), we obtain μ μ c H = n E ϵ ϵ c E = n H , where H and E are the magnitudes of H and E. Multiplying the last two equations gives