A plane electromagnetic wave of frequency $500 \mathrm{MHz}$ is traveling in a vacuum along the $y-$direction. At a particular point in space and time, $\overrightarrow{B}=8.0\times {10}^{-8}\hat{\mathrm{z}} \mathrm{T}$. The value of the electric field at this point is:(speed of light $=3\times {10}^8{ \mathrm{ms}}^{-1}$) $\hat{\mathrm{x}},\hat{\mathrm{y}},\hat{\mathrm{z}}$ are unit vectors along $x,y$ and $z$ direction.