The nature of electromagnetic wave is

In electromagnetic waves,the average energy density is associated with what?

The velocity of an electromagnetic wave is in the direction of

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:

In an apparatus, the electric field was found to oscillate with an amplitude of $18 \text{ V/m}$. The magnitude of the oscillating magnetic field will be:

$A$ plane electromagnetic wave of frequency $25 \text{ MHz}$ travels in free space along the $X$-direction. At a particular point in space and time,the magnetic field is $\overrightarrow{B} = 2.1 \times 10^{-8} \hat{k} \text{ T}$. Find the electric field $\overrightarrow{E}$ at this point.