$A$ laser beam is operating at $100 \,mW$. The amount of energy stored by $90 \,cm$ length of this laser beam will be

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

The energy that will be ideally radiated by a $100\,kW$ transmitter in $1$ hour is:

The electromagnetic flux from the Sun reaching the Earth is $10^3 \ W m^{-2}$. What is the power incident on a roof of dimensions $6 \ m \times 30 \ m$?

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?