For a radiation of $9 \text{ GHz}$ passing through air,the number of waves passing through $1 \text{ m}$ length is . . . . . . .

$A$ lamp emits monochromatic green light uniformly in all directions. The lamp is $3\%$ efficient in converting electrical power to electromagnetic waves and consumes $100\,W$ of power. The amplitude of the electric field associated with the electromagnetic radiation at a distance of $5\,m$ from the lamp will be nearly.......$V/m$

$A$ plane electromagnetic wave travelling along the $X$-direction has a wavelength of $3 \ mm$. The variation in the electric field occurs in the $Y$-direction with an amplitude of $66 \ Vm^{-1}$. The equations for the electric and magnetic fields as a function of $x$ and $t$ are respectively:

For plane electromagnetic waves propagating in the positive $Z$-direction,the combination which gives the correct possible direction for $\vec{E}$ and $\vec{B}$ fields respectively is:

The electric field in a plane electromagnetic wave is given by $E = 50 \sin(500x - 10 \times 10^{10}t) \, V/m$. The velocity of the electromagnetic wave in this medium is: (Given $C = \text{speed of light in vacuum}$)

The biological importance of the ozone layer is that: