1. The problem statement, all variables and given/known data When an EM wave propagates, the E and M field at a point are perpendicular. If E and M at a point are NOT perpendicular to each other, can it be that an EM wave is passing through that point? 2. Relevant equations 3. The attempt at a solution Consider a linearly polarized light travelling. If I create a constant electric field(by using a device, for example a "saturated" capacitor), the light won't vanish as the energy won't be conserved. So an EM wave MAY be propagating. I don't know if this is correct.