An electromagnetic wave has an electric field given by

E$($y$,$t$)=[2\mathrm{.}20105$V$/$mcos$($ky$(1\mathrm{.}0851013$rad$/$s$)$t$)]$k$^$E$($y$,$t$)=[2\mathrm{.}20105$V$/$mcos$($ky$(1\mathrm{.}0851013$rad$/$s$)$t$)]$k$^.$