The figure shows the electric field overright | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) The direction of propagation of an $EM$ wave is given by the direction of the Poynting vector $\overrightarrow{S}$,which is in the direction of $\

Vedclass · Accepted Answer

Towards $+x$ direction

Vedclass · Answer

(A) The direction of propagation of an $EM$ wave is given by the direction of the Poynting vector $\overrightarrow{S}$,which is in the direction of $\overrightarrow{E} 	imes \overrightarrow{B}$.Given,the direction of propagation is $-z$ direction,so $\overrightarrow{E} 	imes \overrightarrow{B} = -\widehat{k}$.From the figure,the electric field $\overrightarrow{E}$ is in the $+y$ direction,so $\overrightarrow{E} = E_0 \widehat{j}$.Substituting these into the relation: $(E_0 \widehat{j}) 	imes \overrightarrow{B} = -\widehat{k}$.Let $\overrightarrow{B} = B_x \widehat{i} + B_y \widehat{j} + B_z \widehat{k}$.Since $\overrightarrow{E} \perp \overrightarrow{B}$ and $\overrightarrow{B} \perp 	ext{propagation direction}$,$\overrightarrow{B}$ must be along the $x$-axis.So,$\widehat{j} 	imes (B_x \widehat{i}) = -B_x \widehat{k}$.Comparing this with $-\widehat{k}$,we get $-B_x = -1$,which means $B_x = 1$.Therefore,the magnetic field $\overrightarrow{B}$ is in the $+x$ direction.

The figure shows the electric field $\overrightarrow{E}$ of an $EM$ wave at a certain point and a certain instant. The wave is transporting energy in the negative $z$ direction ($-z$ direction). What is the direction of the magnetic field $\overrightarrow{B}$ of the wave at that point and instant?

Similar Questions

Select the correct statement from the following:

The ratio of the magnitudes of the electric field to the magnetic field of an electromagnetic wave is of the order of

Assertion : Radio waves can be polarised.
Reason : Sound waves in air are longitudinal in nature.

An electromagnetic wave with angular frequency $\omega$ and wavelength $\lambda$ propagates in the $+y$ direction. Its magnetic field is directed along the $-x$ direction. The vector expression for the associated electric field (with amplitude $E_0$) is ...........

In vacuum,the speed of light depends upon

Vedclass Test Series

Exam Paper Generator

Online Exam Module