A particle of mass $\mathrm{m}$ and charge $\mathrm{q}$ has an initial velocity $\overline{\mathrm{v}}=\mathrm{v}_{0} \hat{\mathrm{j}} .$ If an electric field $\overrightarrow{\mathrm{E}}=\mathrm{E}_{0} \hat{\mathrm{i}}$ and magnetic field $\overrightarrow{\mathrm{B}}=\mathrm{B}_{0} \hat{\mathrm{i}}$ act on the particle, its speed will double after a time:
$\frac{{2} m v_{0}}{q E_{0}}$
$\frac{\sqrt{2} m v_{0}}{q E_{0}}$
$\frac{\sqrt{3} m v_{0}}{q E_{0}}$
$\frac{{3} m v_{0}}{q E_{0}}$
In the given electromagnetic wave $E_y=600 \sin (\omega t-k x) \mathrm{Vm}^{-1}$, intensity of the associated light beam is (in $\mathrm{W} / \mathrm{m}^2$ ); (Given $\epsilon_0=$ $\left.9 \times 10^{-12} \mathrm{C}^{-2} \mathrm{~N}^{-1} \mathrm{~m}^{-2}\right)$
The magnetic field in a plane electromagnetic wave is given by
${B_y} = \left( {2 \times {{10}^{ - 7}}} \right)\sin \left( {0.5 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)T$
$(a)$ What is the wavelength and frequency of the wave?
$(b)$ Write an expression for the electric field.
A plane electromagnetic wave is travelling in the positive $X-$axis. At the instant shown electric field at the extremely narrow dashed rectangle is in the $-ve$ $z$ direction and its magnitude is increasing. Which diagram correctly shows the direction and relative magnitudes of magnetic field at the edges of rectangle :-
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
Energy stored in electromagnetic oscillations is in the form of