A plane electro magnetic wave of frequency $25\;MHz$ travels in free space along the x- direction At a particular point in space and time the electric vector $\overrightarrow{E}= 6.3 v/m \hat j$. calculate $\overrightarrow{B}$ at this point .

Question

$\begin{array}{1 1} 2.1 \times 10^{-7} \hat k \;t \\ 2.1 \times 10^{-8} \hat k \;t \\ 2.1 \times 10^{-8} \hat j \;t \\ 2.1 \times 10^{-7} \hat j \;t \end{array} $