Now to solve for E r a d , we take the curl of the third equation in the first set of Maxwell equation and combine it with the fourth. ∇ ∇ × × ∇ ∇ × × E r a d = − − ∂ ∂ ∂ ∂ t ( ∇ ∇ × × B r a d ) ∇ ∇ × × ∇ ∇ × × E r a d = − − ∂ ∂ ∂ ∂ t ( μ μ 0 J + ϵ ϵ 0 μ μ 0 ∂ ∂ E r a d ∂ ∂ t )