1. The problem statement, all variables and given/known data derive the following wave equation ∇2H = 1/c2 (∂2H/∂t2) 2. Relevant equations 3. The attempt at a solution I'm not sure how to derive it. I suppose I can break it into a whole bunch of partial derivatives because of the del squared operator and then just lump the three partial derivatives (Hx, Hy, Hz) back into H but I don't know if that's a derivation of the equation.