Long-distance radio broadcasting uses which of the following waves?

The unit of $\sqrt{\frac{2 I}{\varepsilon_0 c}}$ is
($I$: intensity of an electromagnetic wave,$c$: speed of light)

For electromagnetic waves,the phase difference between the $\vec{E}$ and $\vec{B}$ vectors (for the region far from the source) is......

For an electromagnetic wave,the electric field is given by $E_x = 36 \sin(1.20 \times 10^7 z - 3.6 \times 10^{15} t) \ V/m$. What is the intensity of the electric field in $W/m^2$?

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 $mW \ m^{-2}$)

In an electromagnetic wave,the phase difference between the electric and magnetic field vectors $\vec{E}$ and $\vec{B}$ is: