Write Maxwells equations in point form in terms of E and H as they apply to a sourceless medium, where J and v are

Write Maxwell’s equations in point form in terms of E and H as they apply to a sourceless medium, where J and ρ_v are both zero. Replace ∈ by μ, μ by ∈, E by H, and H by − E, and show that the equations are unchanged. This is a more general expression of the duality principle in circuit theory.