Consider a plane electromagnetic wave such as that shown in Fig. 325, but in which E and B also have components in the x-direction (along the direction of wave propagation). Use Gauss's law for electric and magnetic fields to show that the components E. and B. must both be equal to zero so that the fields E and B are both transverse. (Hint: Use a Gaussian surface like that shown in Fig. 32.6. Of the two faces parallel to the yz-plane, choose one to be to the left of the wave front and the other to be to the right of the wave front.)