$8\mathrm{.}29$ Aplane wave in air with e Ei $=$ y$20$e$$j$(3$x$+4$z$)($V$/$m$)$ is incident upon the planar surface of a dielectric material with r $=4,$ and it occupies the half$-$space z $0.$ Determine: $($a$)$ the polarization of the incident wave, $($b$)$ the angle of incidence, $($c$)$ the time$-$domain expressions for the reflected electric and magnetic fields, $($d$)$ the time$-$domain expressions for the transmitted electric and magnetic fields, and $($e$)$ the average power density carried by the wave in the dielectric medium.