The electric field associated with an electromagnetic wave propagating in a dielectric medium is given by 
$\overrightarrow{\mathrm{E}}=30(2\widehat{\mathrm{x}}+\widehat{\mathrm{y}})\sin \left[2\mathrm{\pi }\left(5\times {10}^{14}\mathrm{t}-\frac{{10}^7}{3}\mathrm{z}\right)\right]{\mathrm{Vm}}^{-1}.$Which of the following option(s) is(are) correct? [Given: The speed of light in vacuum  $\left.\mathrm{c}=3\times {10}^8{\mathrm{ms}}^{-1}\right]$

$\begin{array}{l}\overrightarrow{\mathrm{E}}=30(2\widehat{\mathrm{x}}+\widehat{\mathrm{y}})\sin \left[2\mathrm{\pi }\left(5\times {10}^{14}\mathrm{t}-\frac{{10}^7}{3}\mathrm{z}\right)\right]\\ \mathrm{w}=2\mathrm{\pi }\left(5\times {10}^{14}\right)\mathrm{k}=2\mathrm{\pi }\times \frac{{10}^7}{3}\Rightarrow \mathrm{v}=\frac{\mathrm{w}}{\mathrm{k}}=\frac{5\times {10}^{14}\times 3}{{10}^7}=3\times {10}^7\times 5\end{array}$
Hence, $\mathrm{\mu }=\frac{\mathrm{c}}{\mathrm{v}}=\frac{3\times {10}^8}{3\times {10}^7\times 5}=\frac{10}{5}=2$
$\frac{\mathrm{E}}{\mathrm{B}}=\mathrm{v}\text{, }$Hence, $\mathrm{B}=\frac{\mathrm{E}}{\mathrm{V}}=\frac{30\sqrt{5}\times 2}{3\times {10}^8}$
Taking B is perpendicular to V and considering  ${\mathrm{E}}^{-1}\times {\mathrm{B}}^{-1}$ is along propagation
So is along -ve  x-axis and thing along the y-axis
${\mathrm{B}}_{\mathrm{n}}=\frac{-30\sqrt{5}\times 2}{3\times {10}^8}\times \frac{1}{\sqrt{5}}=-2\times {10}^{-7}$