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

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

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

$q_1, q_2, q_3$ and $q_4$ are point charges located at point as shown in the figure and  $S$ is a spherical Gaussian surface of radius $R$. Which of the following is true  according to the Gauss's law 
The correct formula for fringe visibility is
In an ac generator, a rectangular coil of $100$ turns each having area $14 \times 10^{-2}\,m ^2$ is rotated at $360\,rev / min$ about an axis perpendicular to a uniform magnetic field of magnitude $3.0 T$. The maximum value of the emf produced will be $............V$. $\left(\right.$ Take $\left.\pi=\frac{22}{7}\right)$
Sun radiates continuously and maintains its brightness because
An infinitely long thin non-conducting wire is parallel to the $z$-axis and carries a uniform line charge density $\lambda$. It pierces a thin non-conducting spherical shell of radius $R$ in such a way that the arc $PQ$ subtends an angle $120^{\circ}$ at the centre $O$ of the spherical shell, as shown in the figure. The permittivity of free space is $\in_0$. Which of the following statements is (are) true?

$(A)$ The electric flux through the shell is $\sqrt{3} R \lambda / \in_0$

$(B)$ The z-component of the electric field is zero at all the points on the surface of the shell

$(C)$ The electric flux through the shell is $\sqrt{2} R \lambda / \in_0$

$(D)$ The electric field is normal to the surface of the shell at all points

The maximum illumination on a screen at a distance of 2 m from a lamp is 25 lux. The value of total luminous flux emitted by the lamp is
Total internal reflection of light is possible when light enters from
Wavelength of, monochromatic light is $5000  A^o$. It's wave number is:
The three resistance of equal value are arranged in the different combinations shown below. Arrange them in increasing order of power dissipation.
A 100% efficient transformer has 100 turns in the primary and 25 turns in its secondary coil. If the current in the secondary coil is 4 amp, then the current in the primary coil is