An electric field wave propagating in the k direction may be written E(r,t)=E,e gi(k.r-wt) By writing E, k and, r in terms of their Cartesian components or otherwise, show that; (a) ¿E=ik.E (b) curl E=ik × E (c) Use the result (and corresponding result for the B field) to show that the E field, the B field, and the direction of propagation are mutually perpendicular.