Suppose that the electric field part of an electromagnetic wave in vaccum is $E= 3.1 \times N/c $ an $[(1/8 rad/m)y +(5.4 \times 10^8\;rad/s/t)$ write an expression for the magnetic field part of the wave

Question

$\begin{array}{1 1} 1.03 \cos [1.8\;y + (5.4 \times 10^8)t ] \hat k \\ 10.3 \sin [1.8\;y + (5.4 \times 10^8)t ] \hat k \\ 10.3 \cos [1.8\;y + (5.4 \times 10^8)t ] \hat k \\ 1.03 \cos [1.8\;y + (5.4 \times 10^8)t ] \hat k \end{array} $