The power radiated from a linear antenna of length $l$ is proportional to (Given,$\lambda =$ wavelength of the wave):

Assertion : Environmental damage has increased the amount of ozone in the atmosphere.
Reason : Increase of ozone increases the amount of ultraviolet radiation on earth.

The electric field of a plane electromagnetic wave is given by $\overrightarrow{E} = E_{0} \frac{\hat{i}+\hat{j}}{\sqrt{2}} \cos (kz+\omega t)$. At $t=0$,a positively charged particle is at the point $(x, y, z) = (0, 0, \frac{\pi}{k})$. If its instantaneous velocity at $t=0$ is $v_{0} \hat{k}$,the force acting on it due to the wave is

The electric field intensity produced by the radiation coming from a $100 \, W$ bulb at a distance of $3 \, m$ is $E$. The electric field intensity produced by the radiation coming from a $60 \, W$ bulb at the same distance is $\sqrt{\frac{x}{5}} E$. The value of $x$ is ......... .

This question has Statement $-1$ and Statement $-2.$ Of the four choices given after the Statements,choose the one that best describes the two Statements.
Statement $-1:$ Short wave transmission is achieved due to the total internal reflection of the $e-m$ wave from an appropriate height in the ionosphere.
Statement $-2:$ Refractive index of the ionosphere is independent of the frequency of $e-m$ waves.

The dimensional formula for the physical quantity $\frac{E^2 \mu_0 \varepsilon_0}{B^2}$ is ($E =$ electric field and $B =$ magnetic field).