In a plane electromagnetic wave, which of the following has/ have zero average/value in one complete cycle?

$(a)$ Magnetic field

$(b)$ Magnetic energy

$(c)$ Electric field

$(d)$ Electric energy

A TV tower has a height of 100 m. The average population density around the tower is 1000 per $km^2$. The radius of the earth is $6.4 \times {10^6}$m. the population covered by the tower is

The property which is not of an electromagnetic wave travelling in free space is that:

In an electromagnetic wave, at an instant and at a particular position, the electric field is along the negative $z$-axis and magnetic field is along the positive $x$-axis. Then the direction of propagation of electromagnetic wave is

The electric field of a plane polarized electromagnetic wave in free space at time $t = 0$ is given by an expression

$\vec E(x,y) = 10\hat j\, cos[(6x + 8z)]$

The magnetic field $\vec B (x,z, t)$ is given by : ($c$ is the velocity of light)