A $3\mathrm{.}5$ mW He$-$Ne laser $($l $=632\mathrm{.}8$ nm$)$ produces a polarized beam of cross$-$sectional area $510-6$ m$2.$ What is the peak electric field in the beam? $($a$)1450$ V$/$m $($b$)726$ V$/$m $($c$)700$ V$/$m $($d$)633$ V$/$m $($e$)514$ V$/$m