The ratio of the electric field $(E)$ to the magnetic field $(B)$ in an electromagnetic wave gives which physical quantity?

In an electromagnetic wave,at an instant and at a particular position,the electric field is along the negative $z$-axis and the magnetic field is along the positive $x$-axis. Then the direction of propagation of the electromagnetic wave is

$A$ point source of electromagnetic radiation has an average power output of $800 \, W$. The maximum value of the electric field at a distance $4.0 \, m$ from the source is .... $V/m$.

$A$ plane electromagnetic wave is moving in free space with velocity $c = 3 \times 10^8 \ m/s$ and its electric field is given as $\vec{E} = 54 \sin(kz - \omega t) \hat{j} \ V/m$, where $\hat{j}$ is the unit vector along the $y$-axis. The magnetic field vector $\vec{B}$ of the wave is:

The electric field for a plane electromagnetic wave travelling in the $+y$ direction is shown. Consider a point where $\vec E$ is in the $+z$ direction. The $\vec B$ field is

For an electromagnetic wave propagating through vacuum, $\vec{k}$, $\vec{E}$, and $\omega$ represent the propagation vector, electric field, and angular frequency, respectively. The magnetic field associated with this wave is represented by: