All electromagnetic wave is transporting energy in the negative z… - Vidyadip

MCQ

All electromagnetic wave is transporting energy in the negative $z$ direction. At a certain point and certain time the direction of electric field of the wave is along positive y direction. What will be the direction of the magnetic field of the wave at that point and instant?

✓
Positive direction of $x$
B
Positive direction of $z$
C
Negative direction of $x$
D
Negative direction of $y$

✓

Answer

Correct option: A.

Positive direction of $x$

a
As, poynting vector

$\overrightarrow{ S }=\overrightarrow{ E } \times \overrightarrow{ H }$

Given energy transport $=$ negative $z$ direction Electric field $=$ positive $y$ direction

$(-\hat{ k })=(+\hat{ j }) \times[\hat{ i }]$

Hence according to vector cross product magnetic field should be positive $x$ direction.

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

Explore more

NEET STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

Two coils have mutual inductance $0.002 \ \mathrm{H}$. The current changes in the first coil according to the relation $\mathrm{i}=\mathrm{i}_0 \sin \omega \mathrm{t}$, where $\mathrm{i}_0=5 \mathrm{~A}$ and $\omega=50 \pi$ $\mathrm{rad} / \mathrm{s}$. The maximum value of $\mathrm{emf}$ in the second coil is $\frac{\pi}{\alpha} \mathrm{V}$. The value of $\alpha$ is_______.

From a tower of height $H$, a particle is thrown vertically upwards with a speed $ u$. The time taken by the particle, to hit the ground, is $n$ times that taken by it to reach the highest point of its path. The relation between $H, u$ and $n$ is:

A cylindrical vessel of cross-section $A$ contains water to a height $h$ . There is a hole in the bottom of radius $'a'$ . The time in which it will be emptied is

The potential barrier, in the depletion layer, is due to

Excess pressure of one soap bubble is four times more than the other. Then the ratio of volume of first bubble to another one is

The sun's diameter is $1.4 \times {10^9}m$ and its distance from the earth is ${10^{11}}m.$ The diameter of its image, formed by a convex lens of focal length $2\,m$ will be.......$cm$

In an $RC$ circuit while charging, the graph of in $i$ versus time is as shown by the dotted line in the diagram figure, where $i$ is the current. When the value of the resistance is doubled, which of the solid curve best represents the variation of in $i$ versus time

$1$ wire mesh consisting of very small squares is viewed at a distance of $S\,cm$ through a magnifying converging lens of focal length $10\,cm$, kept close to the eye. The magnification produced by the lens is

In the circuit shown in the figure below, which of the following statement is incorrect ?

A Young's double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is