MCQ
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
  • A
    $\vec E =  - {E_0}\,\cos \,\left( {\omega t + \frac{{2\pi }}{\lambda }y} \right)\hat x$
  • B
    $\vec E =   {E_0}\,\cos \,\left( {\omega t - \frac{{2\pi }}{\lambda }y} \right)\hat x$
  • $\vec E =   {E_0}\,\cos \,\left( {\omega t - \frac{{2\pi }}{\lambda }y} \right)\hat z$
  • D
    $\vec E = -  {E_0}\,\cos \,\left( {\omega t + \frac{{2\pi }}{\lambda }y} \right)\hat z$

Answer

Correct option: C.
$\vec E =   {E_0}\,\cos \,\left( {\omega t - \frac{{2\pi }}{\lambda }y} \right)\hat z$
c
In an electromagnetic wave electric field and magnetic field are perpendicular to the direction of propagation of wave. The vector equation for the electric field is

$\vec E =   {E_0}\,\cos \,\left( {\omega t - \frac{{2\pi }}{\lambda }y} \right)\hat z$

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