An electromagnetic wave with frequency $\omega $ and wavelength $\lambda $ travels in the $+y$ direction. Its magnetic field is along $+x$ axis. The vector equation for the associated electric field (of amplitude $E_0$) is
$\vec E = {E_{0\,}}\,\cos \left( {\omega t - \frac{{2\pi }}{\lambda }y} \right)\hat x$
$\vec E = -{E_{0\,}}\,\cos \left( {\omega t + \frac{{2\pi }}{\lambda }y} \right)\hat x$
$\vec E = -{E_{0\,}}\,\cos \left( {\omega t + \frac{{2\pi }}{\lambda }y} \right)\hat z$
$\vec E = {E_{0\,}}\,\cos \left( {\omega t - \frac{{2\pi }}{\lambda }y} \right)\hat z$
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. $\left[c=3 \times 10^{8} \;m s ^{-1} .\right]$
Aplane electromagnetic wave is incident on a plane surface of area A normally, and is perfectly reflected. If energy $E$ strikes the surface in time $t$ then average pressure exerted on the surface is ( $c=$ speed of light)
The energy of an electromagnetic wave contained in a small volume oscillates with
Assume a bulb of efficiency $2.5\%$ as a point source. The peak values of electric field produced by the radiation coming from a $100\, W$ bulb at a distance of $3\, m$ is respectively.....$V\,{m^{ - 1}}$
A plane electromagnetic wave in a non-magnetic dielectric medium is given by $\vec E\, = \,{\vec E_0}\,(4 \times {10^{ - 7}}\,x - 50t)$ with distance being in meter and time in seconds. The dielectric constant of the medium is