Show that the mode TE00 cannot occur in a rectangular wave guide. [Hint: In this case ω/c=k, so Eqs. 9.180 are indeterminate, and you must go back to Eq. 9.179. Show that Bz is a constant, and hence---applying Faraday's law in integral form to a cross section---that Bz=0, so this would be a TEM mode.]