Due to the tilting of the Earth,which waves finally disappear?

$A$ radar sends an electromagnetic signal with an electric field $E_{0} = 2.25\,V/m$ and a magnetic field $B_{0} = 1.5 \times 10^{-8}\,T$,which strikes a target on the line of sight at a distance of $3\,km$ in a medium. After that,a part of the signal (echo) reflects back towards the radar with the same velocity and along the same path. If the signal was transmitted at time $t_{0}$ from the radar,then after how much time (in $\times 10^{-5}\,s$) will the echo reach the radar?

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

When an airplane flies over a television antenna,the picture on the $TV$ screen appears to flicker or shake slightly. This is due to:

$A$ microwave and an ultrasonic sound wave have the same wavelength. Their frequencies are in the ratio (approximately):

If two linear antennas having lengths in the ratio $2: 3$ are emitting radiation of wavelengths in the ratio $8: 9$, then the ratio of effective powers radiated by them are in the ratio