In a plane electromagnetic wave,which of the following has/have a zero average value in one complete cycle?
$(a)$ Magnetic field
$(b)$ Magnetic energy
$(c)$ Electric field
$(d)$ Electric energy

In an electromagnetic wave,the electric field vector and magnetic field vector are given as $\vec{E} = E_{0} \hat{i}$ and $\vec{B} = B_{0} \hat{k}$ respectively. The direction of propagation of the electromagnetic wave is along:

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

$A$ plane electromagnetic wave is travelling in the positive $X$-axis. At the instant shown,the electric field at the extremely narrow dashed rectangle is in the $-ve$ $Z$-direction and its magnitude is increasing. Which diagram correctly shows the direction and relative magnitudes of the magnetic field at the edges of the rectangle?

$A$ cube of unit volume contains $35 \times 10^7$ photons of frequency $10^{15} \text{ Hz}$. If the energy of all the photons is viewed as the average energy being contained in the electromagnetic waves within the same volume,then the amplitude of the magnetic field is $\alpha \times 10^{-9} \text{ T}$. Taking permeability of free space $\mu_0 = 4\pi \times 10^{-7} \text{ Tm/A}$,Planck's constant $h = 6 \times 10^{-34} \text{ Js}$ and $\pi = \frac{22}{7}$,the value of $\alpha$ is $.....$

In a plane electromagnetic wave,the maximum value of the electric field component is $4.4 \ Vm^{-1}$. The intensity of the wave is nearly (in $mW \ m^{-2}$)