The velocity of an electromagnetic wave is in the direction of

Electromagnetic waves are:

$A$ plane electromagnetic wave travels in a medium of relative permeability $\mu_{r} = 1.61$ and relative permittivity $\epsilon_{r} = 6.44$. If the magnitude of the magnetic intensity $H$ is $4.5 \times 10^{-2} \; A m^{-1}$ at a point,what will be the approximate magnitude of the electric field intensity $E$ at that point? (Given: $\mu_{0} = 4 \pi \times 10^{-7} \; N A^{-2}$,$c = 3 \times 10^{8} \; m s^{-1}$)

The Poynting vector $\vec S$ is defined as a vector whose magnitude is equal to the wave intensity and whose direction is along the direction of wave propagation. Mathematically,it is given by $\vec S = \frac{1}{{\mu _0}}(\vec E \times \vec B)$. Show the nature of the $\vec S$ vs $t$ graph.

The following travelling electromagnetic wave $E_x=0$,$E_y=E_0 \sin (kx + \omega t)$,$E_z=-2E_0 \sin (kx - \omega t)$ is:

An electromagnetic wave travels along the $z$-axis. Which of the following pairs of space and time-varying fields would generate such a wave?