A plane electromagnetic wave of frequency $500\, MHz$ is travelling in vacuum along $y-$direction. At a particular point in space and

time, $\overrightarrow{ B }=8.0 \times 10^{-8} \hat{ z } \;T$. The value of electric field at this point is

(speed of light $\left.=3 \times 10^{8}\, ms ^{-1}\right)$

$\hat{ x }, \hat{ y }, \hat{ z }$ are unit vectors along $x , y$ and $z$ direction.

In the $EM$ wave the amplitude of magnetic field $H_0$ and the amplitude of electric field $E_o$ at any place are related as

If $\vec{E}$ and $\vec{K}$ represent electric field and propagation vectors of the EM waves in vacuum, then magnetic field vector is given by : $(\omega-$ angular frequency) :

The energy density associated with electric field $\overrightarrow{ E }$ and magnetic field $B$ of an electromagnetic wave in free space is given by ( $\epsilon_0-$ permittivity of free space, $\mu_0$ – permeability of free space)

The electric field of a plane electromagnetic wave propagating along the $x$ direction in vacuum is $\overrightarrow{ E }= E _{0} \hat{ j } \cos (\omega t – kx )$. The magnetic field $\overrightarrow{ B },$ at the moment $t =0$ is :