EM Waves — JEE Main PYQs

A radiation is emitted by 1000 W bulb and it generates an electric field and magnetic field at P , placed at a distance of 2 m . The efficiency of the bulb is $1.25\%$. The value of peak electric field at $P$ is $x\times 10^{-1}\mathrm{V}/\mathrm{m}$. Value of $x$ is ------ …

If E and H represents the intensity of electric field and magnetising field respectively, then the unit of $E/H$ will be:

Electric field in a plane electromagnetic wave is given by

The velocity of electromagnetic wave in this medium is :
(Given C = speed of light in vacuum)

A transmitting antenna has a height of 320 m and that of receiving antenna is 2000 m. The maximum distance between them for satisfactory communication in line of sight mode is 'd'. The value of 'd' is ______ km.

The electric field in an electromagnetic wave is given by $E=(50{\mathrm{NC}}^{-1})\sin \omega (t-x/c)$
The energy contained in a cylinder of volume V is $5.5\times 10^{-12}\mathrm{J}$. The value of V is _____ ${\mathrm{cm}}^3$.
(given …

If the sum of the heights of transmitting and receiving antennas in the line of sight of communication is fixed at 160 m, then the maximum range of LOS communication is ______ km. (Take radius of Earth $=6400\mathrm{km}$)

The relative permittivity of distilled water is 81. The velocity of light in it will be: (Given ${\mu }_{\mathrm{r}}=1$)

For VHF signal broadcasting ______ ${\mathrm{km}}^2$ of maximum service area will be covered by an antenna tower of height 30 m , if the receiving antenna is placed at ground. Let radius of the earth be 6400 km . (Round off to the Nearest Integer) (Take $\pi$ as 3.14)

If $2.5\times 10^{-6}\mathrm{N}$ average force is exerted by a light wave on a non- reflecting surface of $30{\mathrm{cm}}^2$ area during 40 minutes of time span, the energy flux of light just before it falls on the surface is ______ $\mathrm{W}/{\mathrm{cm}}^2$. (Rou …

A linearly polarized electromagnetic wave in vacuum is
$\mathrm{E}=3.1\cos \left[(1.8)\mathrm{z}-\left(5.4\times 10^6\right)\mathrm{t}\right]\hat{\mathrm{i}}\mathrm{N}/\mathrm{C}$
Is incident normally on a perfectly reflecting wall at $\mathrm{z}=\mathrm{a}$. Choose the …

Electric field of a plane electromagnetic wave propagating through a non-magnetic medium is given by $E=20\cos \left(2\times 10^{10}t-200x\right)V/m$. The dielectric constant of the medium is equal to: (Take ${\mu }_{\mathrm{r}}=1$)

A plane electromagnetic wave of frequency 500 MHz is traveling in vacuum along y-direction. At a particular point in space and time, $\vec{B}=8.0\times 10^{-8}\hat{z}T$. The value of electric field at this point is: $($ speed of light …

A 25 m long antenna is mounted on an antenna tower. The height of the antenna tower is 75 m . The wavelength (in meter) of the signal transmitted by this antenna would be:

For an electromagnetic wave traveling in free space, the relation between average energy densities due to electric ( ${\mathrm{U}}_{\mathrm{e}}$ ) and magnetic ( ${\mathrm{U}}_{\mathrm{m}}$ ) fields is :

Two identical antennas on identical towers are separated from each other by a distance of 45 km . What should be the minimum height of receiving antenna to receive the signals in line of sight? (Assume radius of earth is 6400 km )

A plane electromagnetic wave propagating along y-direction, can have the following pair of electric field ($\vec{E}$) and magnetic field ($\vec{B}$) components :

A TV transmission tower antenna is at a height of 20 m. Suppose that the receiving antenna is at
(i) ground level
(ii) a height of 5 m

The increase in the antenna range in case (ii) relative to case (i) is $n\%$.
The value of n, to the nearest integer, is ____

The electric field intensity produced by the radiation coming from a 100 W bulb at a distance of 3 m is E. The electric field intensity produced by the radiation coming from 60 W at the same distance is $\sqrt{\frac{x}{5}}E$. Where the value of $x=$ ______

Sea-water at a frequency $\mathrm{f}=9\times 10^2\mathrm{Hz}$, has permittivity $\epsilon =80{\epsilon }_0$ and resistivity $\rho =0.25\Omega \mathrm{m}$. Imagine a parallel plate capacitor is immersed in seawater and is driven by an alternating voltage source …

A plane electromagnetic wave of frequency 100 MHz is traveling in vacuum along the x -direction. At a particular point in space and time, $\overrightarrow{\mathrm{B}}=2.0\times 10^{-8}\hat{\mathrm{k}}\mathrm{T}$. (where, $\hat{\mathrm{k}}$ is unit vector along z -direction …

If the magnetic field in a plane electromagnetic wav is given by $\overrightarrow{\mathrm{B}}=3\times 10^{-8}\sin \left(1.6\times 10^3\mathrm{x}+48\times 10^{10}\mathrm{t}\right)\mathrm{jT}$, then what will be expression for electric field?

The electric field of a plane electromagnetic wave is given by

At $t=0$, a positively charged particle is at the point …

A plane electromagnetic wave of frequency 25 GHz is propagating in vacuum along the z-direction. At a particular point in space and time, the magnetic field is given by $\vec{B}=5\times 10^{-8}\hat{j}\mathrm{T}$. The corresponding electric field $\vec{E}$ is (speed of light …

A plane electromagnetic wave is propagating along the direction $\frac{\hat{i}+\hat{j}}{\sqrt{2}}$, with its polarization along the direction $\hat{\mathrm{k}}$. The correct form of the magnetic field of the wave would be (here ${\mathrm{B}}_0$ is an appropriate constant)

The electric fields of two plane electromagnetic plane waves in vacuum are given by ${\overrightarrow{\mathrm{E}}}_1={\mathrm{E}}_0\hat{\mathrm{j}}\cos (\omega \mathrm{t}-\mathrm{kx})$ and …

The correct match between the entries in column I and column II are:

Radiation
(a) Microwave
(b) Gamma rays
(c) A.M. radio waves
(d) X-rays

Wavelength
(i) 100 m
(ii) $10^{-15}\mathrm{m}$
(iii) $10^{-10}\mathrm{m}$
(iv) $10^{-3}\mathrm{m}$

The magnetic field of a plane electromagnetic wave is

where $\mathrm{c}=3\times 10^8{\mathrm{ms}}^{-1}$ is the speed of light.
The corresponding electric field is

The electric field of a plane electromagnetic wave propagating along the $x$ direction in vacuum is $\vec{E}=E_0\hat{j}\cos (\omega t-kx)$. The magnetic field $\vec{B}$, at the moment $t=0$ is:

For a plane electromagnetic wave, the magnetic field at a point $x$ and time $t$ is $\vec{B}(x,t)=\left[1.2\times 10^{-7}\sin \left(0.5\times 10^{3}x+1.5\times 10^{11}t\right)\hat{k}\right]T$

The instantaneous electric field $\vec{E}$ corresponding to $\vec{B}$ is: (spe …

An electron is constrained to move along the y - axis with a speed of 0.1 c (c is the speed of light) in the presence of electromagnetic wave, whose electric field is …

Suppose that intensity of a laser is $\left(\frac{315}{\pi }\right)\mathrm{W}/{\mathrm{m}}^2$. The rms electric field, in units of $\mathrm{V}/\mathrm{m}$ associated with this source is close to the nearest integer is ____. …

Choose the correct option relating wavelengths of different parts of electromagnetic wave spectrum:

The electric field of a plane electromagnetic wave is given by $\vec{E}=E_0(\hat{x}+\hat{y})\sin (kz-\omega t)$. Its magnetic field will be given by:

The wavelength of the carrier waves in a modern optical fiber communication network is close to:

A plane electromagnetic wave travels in free space along the x -direction. The electric field component of the wave at a particular point of space and time is $E=6{\mathrm{Vm}}^{-1}$ along y -direction. Its corresponding magnetic filed component, B would be:

The magnetic field of an electromagnetic wave is given by:

The associated electric field will be:

In a line of sight radio communication, a distance of about 50 km is kept between the transmitting and receiving antennas. If the height of the receiving antenna is 70 m, then the minimum height of the transmitting antenna should be: (Radius of the Earth $=6.4\times 10^{6}m$)

The magnetic field of a plane electromagnetic wave is given by: $\overrightarrow{\mathrm{B}}={\mathrm{B}}_0\hat{\mathrm{i}}[\cos (\mathrm{kz}-\omega \mathrm{t})]+{\mathrm{B}}_1\hat{\mathrm{j}}\cos (\mathrm{kz}-\omega \mathrm{t})$ where …

A TV transmission tower has a height of 140 m and the height of the receiving antenna is 40 m. What is the maximum distance upto which signals can be broadcasted from this tower in LOS (Line of Sight) mode? (Given : radius of earth $=6.4\times 10^6\mathrm{m}$).

If the magnetic field of a plane electromagnetic wave is given by (The speed of light = $3\times 10^8\mathrm{m}/\mathrm{s})\mathrm{B}=100\times 10^{-6}\sin \left[2\pi \times 2\times 10^{15}\left(\mathrm{t}-\frac{\mathrm{x}}{\mathrm{c}}\right)\right]$ then …

A 27 mW laser beam has a cross-sectional area of $10{\mathrm{mm}}^2$. The magnitude of the maximum electric field in this electromagnetic wave is given by:
[Given permittivity of space ${ϵ}_0=9\times 10^{-12}\mathrm{SI}$ units, speed of light …

An electromagnetic wave is represented by the electric field $\vec{E}=E_0\hat{n}\sin [\omega t+(6y-8z)]$. Taking unit vectors in $x$, $y$ and $z$ directions to be $\hat{i},\hat{j},\hat{k}$, the direction of propogation $\hat{s}$, is

Light is incident normally on a completely absorbing surface with an energy flux of $25\mathrm{W}{\mathrm{cm}}^{-2}$. If the surface has an area of $25{\mathrm{cm}}^2$, the maximum transferred to the surface in 40 min time duration will be

An electromagnetic wave of intensity $50{\mathrm{Wm}}^{-2}$ enters in a medium of refractive index' ${\mathrm{n}}^{\prime }$ without any loss . The ratio of the magnitudes of electric fields, and the ratio of the magnitudes of magnetic fields of the wave before and after entering …

A light wave is incident normally on a glass slab of refractive index 1.5 . If $4\%$ of light gets reflected and the amplitude of the electric field of the incident light is $30\mathrm{V}/\mathrm{m}$, then the amplitude of the electric field for the wave propagating in t …

A plane electromagnetic wave having a frequency $\mathrm{n}=23.9\mathrm{GHz}$ propagates along the positive z-direction in free space. The peak value of the electric field is $60\mathrm{V}/\mathrm{m}$. Which among the following is the acceptable magnetic field component …

The mean intensity of radiation on the surface of the Sun is about $10^8\mathrm{W}/{\mathrm{m}}^2$. The rms value of the corresponding magnetic field is closet to :

$50\mathrm{W}/{\mathrm{m}}^2$ energy density of sunlight is normally incident on the surface of a solar panel. Some part of incident energy ( $25\%$ ) is reflected from the surface and the rest is absorbed. The force exerted on $1{\mathrm{m}}^2$ surface area will be close …

The energy associated with electric field is $({\mathrm{U}}_{\mathrm{E}})$ and with magnetic field is $({\mathrm{U}}_{\mathrm{B}})$ for an electromagnetic wave in free space. Then:

In a communication system operating at wavelength 800 nm , only one percent of source frequency is available as signal bandwidth. The number of channels accommodated for transmitting TV signals of band width 6 MHz are (Take velocity of light …