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
$\vec E = - {E_0}\,\cos \,\left( {\omega t + \frac{{2\pi }}{\lambda }y} \right)\hat x$
$\vec E = {E_0}\,\cos \,\left( {\omega t - \frac{{2\pi }}{\lambda }y} \right)\hat x$
$\vec E = {E_0}\,\cos \,\left( {\omega t - \frac{{2\pi }}{\lambda }y} \right)\hat z$
$\vec E = - {E_0}\,\cos \,\left( {\omega t + \frac{{2\pi }}{\lambda }y} \right)\hat z$
When $EM$ wave propagates through vacuum then
The electric field in an electromagnetic wave is given by $\overrightarrow{\mathrm{E}}=\hat{\mathrm{i}} 40 \cos \omega\left(\mathrm{t}-\frac{\mathrm{z}}{\mathrm{c}}\right) N \mathrm{NC}^{-1}$. The magnetic field induction of this wave is (in SI unit):
A long straight wire of resistance $R$, radius $a $ and length $ l$ carries a constant current $ I.$ The Poynting vector for the wire will be
The magnetic field of a beam emerging from a filter facing a floodlight is given by B${B_0} = 12 \times {10^{ - 8}}\,\sin \,(1.20 \times {10^7}\,z - 3.60 \times {10^{15}}t)T$. What is the average intensity of the beam ?
Write characteristics of electromagnetic waves.