How much time will it take for information to propagate over a distance of $30 \, km$ in space?

Choose the correct statement.

$A$ plane $EM$ wave travelling along $z-$ direction is described by $\vec E = E_0 \sin(kz - \omega t)\hat i$ and $\vec B = B_0 \sin(kz - \omega t)\hat j$. Show that:
$(i)$ The average energy density of the wave is given by $U_{av} = \frac{1}{4} \epsilon_0 E_0^2 + \frac{1}{4} \frac{B_0^2}{\mu_0}$.
$(ii)$ The time-averaged intensity of the wave is given by $I_{av} = \frac{1}{2} c \epsilon_0 E_0^2$.

If an electromagnetic wave is propagating in the $x$-direction and the magnetic field $\vec{B}$ at any instant is in the $z$-direction,then at that instant,the electric field $\vec{E}$ will be in the ........ direction.

In an electromagnetic wave,the maximum value of the electric field is $18 \, V/m$. What is the maximum value of the magnetic field?

The magnetic field in a plane electromagnetic wave is given by $B_y = (3.5 \times 10^{-7}) \sin (1.5 \times 10^3 x + 0.5 \times 10^{11} t) \ T$. The corresponding electric field will be: