In a certain region uniform electric field $E$ and magnetic field $B$ are present in the opposite direction. At the instant $t = 0,$ a particle of mass $m$ carrying a charge $q$ is given velocity $v_o$ at an angle $\theta ,$ with the $y$ axis, in the $yz$ plane. The time after which the speed of the particle would be minimum is equal to
$\frac{{m{v_o}}}{{qE}}$
$\frac{{m{v_o}\sin \theta }}{{qE}}$
$\frac{{m{v_o}\cos \theta }}{{qE}}$
$\frac{{2\pi m}}{{qB}}$
If $c $ is the speed of electromagnetic waves in vacuum, its speed in a medium of dielectric constant $K$ and relative permeability ${\mu _r}$ is
In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of $2.0 \times 10^{10}\; Hz$ and amplitude $48\; Vm ^{-1}$
$(a)$ What is the wavelength of the wave?
$(b)$ What is the amplitude of the oscillating magnetic field?
$(c)$ Show that the average energy density of the $E$ field equals the average energy density of the $B$ field. $\left[c=3 \times 10^{8} \;m s ^{-1} .\right]$
The electric fields of two plane electromagnetic plane waves in vacuum are given by
$\overrightarrow{\mathrm{E}}_{1}=\mathrm{E}_{0} \hat{\mathrm{j}} \cos (\omega \mathrm{t}-\mathrm{kx})$ and
$\overrightarrow{\mathrm{E}}_{2}=\mathrm{E}_{0} \hat{\mathrm{k}} \cos (\omega \mathrm{t}-\mathrm{ky})$
At $t=0,$ a particle of charge $q$ is at origin with a velocity $\overrightarrow{\mathrm{v}}=0.8 \mathrm{c} \hat{\mathrm{j}}$ ($c$ is the speed of light in vacuum). The instantaneous force experienced by the particle is
What is radiation pressure ?
A plane electromagnetic wave of wave intensity $6\,W/m^2$ strike a small mirror of area $30\,cm^2$ , held perpendicular to a approching wave. The momentum transmitted in $kg\, m/s$ by the wave to the mirror each second will be