The amplitude of the electric field in an electromagnetic wave is $1 \ V/m$. The frequency of the wave is $5 \times 10^{14} \ Hz$. The wave propagates along the $z$-axis. What is the average energy density of the electric field in $J/m^3$?

An electromagnetic wave of frequency $2 \text{ MHz}$ propagates from vacuum to a non-magnetic medium of relative permittivity $9$. Then its wavelength

$A$ plane electromagnetic wave of wavelength $3.0 \ m$ travels in vacuum along the positive $X$-axis. The electric field of amplitude $300 \ Vm^{-1}$ oscillates parallel to the $Y$-axis. Then the intensity of the wave is $(\mu_0 = 4\pi \times 10^{-7} \ Hm^{-1}, c = 3 \times 10^8 \ ms^{-1})$ (in $Wm^{-2}$)

If a source is transmitting electromagnetic waves of frequency $8.2 \times 10^6 \,Hz$, then the wavelength of the electromagnetic waves transmitted from the source will be (in $\,m$)

$A$ 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 $.....$

The amplitude of the magnetic field part of a harmonic electromagnetic wave in vacuum is $B_0 = 510 \; nT$. What is the amplitude of the electric field (in $N/C$) part of the wave?