Solved papers for JEE Main & Advanced Physics EM Waves JEE PYQ-Electro Magnetic Waves

done JEE PYQ-Electro Magnetic Waves Total Questions - 55

• question_answer1) Which of the following are not electromagnetic waves?             [AIEEE 2002]
  A)
  Cosmic-rays
  done clear
  B)
  y-rays
  done clear
  C)
  \[\beta \]-rays
  done clear
  D)
  X-rays
  done clear
  View Answer play_arrow

• question_answer2) Infrared radiations are detected by [AIEEE 2002]
  A)
  spectrometer
  done clear
  B)
  pyrometer
  done clear
  C)
  nanometer
  done clear
  D)
  photometer
  done clear
  View Answer play_arrow

• question_answer3) Which of the following radiations has the least wavelength?                 [AIEEE 2003]
  A)
  \[\gamma \]-rays
  done clear
  B)
  \[\beta \]-rays
  done clear
  C)
  \[\alpha \]-rays
  done clear
  D)
  \[X\]-rays
  done clear
  View Answer play_arrow

• question_answer4) An electromagnetic wave of frequency \[v=3.0MHz\]passes from vacuum into a dielectric medium with permittivity\[\varepsilon =4.0.\] Then,                                       [AIEEE 2004]
  A)
  wavelength is doubled and the frequency remains unchanged
  done clear
  B)
  wavelength is' doubled and frequency becomes half
  done clear
  C)
  wavelength is halved and frequency remains unchanged
  done clear
  D)
  wavelength and frequency  both remain unchanged
  done clear
  View Answer play_arrow

• question_answer5) The rms value of the electric field of the light coming from the sun is 720 N/C. The average total energy density of the electromagnetic wave is                                           [AIEEE 2006]
  A)
  \[4.58\times {{10}^{-6}}J/{{m}^{3}}\]
  done clear
  B)
  \[6.37\times {{10}^{-9}}J/{{m}^{3}}\]
  done clear
  C)
  \[81.35\times {{10}^{-12}}J/{{m}^{3}}\]
  done clear
  D)
  \[3.3\times {{10}^{-3}}J/{{m}^{3}}\]
  done clear
  View Answer play_arrow

• question_answer6) A fully charged capacitor C with initial charge \[{{q}_{0}}\] is connected to a coil of self-inductance L at \[t=0\]. The time at which the energy is stored equally between the electric and the magnetic fields is [AIEEE 2011]
  A)
  \[\sqrt{LC}\]
  done clear
  B)
  \[\pi \sqrt{LC}\]
  done clear
  C)
  \[\frac{\pi }{4}\sqrt{LC}\]
  done clear
  D)
  \[2\pi \sqrt{LC}\]
  done clear
  View Answer play_arrow

• question_answer7) An electromagnetic wave in vacuum has the electric and magnetic field \[\vec{E}\] and \[\vec{B}\], which are always perpendicular to each other. The direction of polarization is given by \[\vec{X}\] and that of wave propagation by \[\vec{k}\]. Then                                                           [AIEEE 2012]
  A)
  \[\vec{X}||\vec{B}\] and \[\vec{k}||\vec{B}\times \vec{E}\]                     
  done clear
  B)
  \[\vec{X}||\vec{E}\] and \[\vec{k}||\vec{E}\times \vec{B}\]
  done clear
  C)
  \[\vec{X}||\vec{B}\] and \[\vec{k}||\vec{E}\times \vec{B}\]
  done clear
  D)
  \[\vec{X}||\vec{E}\] and \[\vec{k}||\vec{B}\times \vec{E}\]
  done clear
  View Answer play_arrow

• question_answer8) An electromagnetic wave with frequency co 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        [JEE ONLINE 19-05-2012]
  A)
  \[\overset{\to }{\mathop{E}}\,=-{{E}_{0}}\cos \left( \omega t+\frac{2\pi }{\lambda }y \right)\hat{x}\]
  done clear
  B)
  \[\overset{\to }{\mathop{E}}\,={{E}_{0}}\cos \left( \omega t-\frac{2\pi }{\lambda }y \right)\hat{x}\]
  done clear
  C)
  \[\overset{\to }{\mathop{E}}\,={{E}_{0}}\cos \left( \omega t-\frac{2\pi }{\lambda }y \right)\hat{z}\]
  done clear
  D)
  \[\overset{\to }{\mathop{E}}\,=-{{E}_{0}}\cos \left( \omega t+\frac{2\pi }{\lambda }y \right)\hat{z}\]
  done clear
  View Answer play_arrow

• question_answer9) A radio transmitter transmits at 830 kHz. At a certain distance from the transmitter magnetic field has amplitude \[4.82\times {{10}^{-11}}T.\]The electric field and the wavelength are respectively[JEE ONLINE 26-05-2012]
  A)
  0.014N/C, 36m
  done clear
  B)
  0.14N/C, 36m
  done clear
  C)
  0.14N/C, 360m
  done clear
  D)
  0.014N/C, 360m
  done clear
  View Answer play_arrow

• question_answer10) The frequency of X-rays; \[\gamma \text{-}\]rays and ultraviolet rays are respectively a, b and c then [JEE ONLINE 26-05-2012]
  A)
  \[a<b;b>c\]
  done clear
  B)
  \[a>b;b>c\]
  done clear
  C)
  \[a<b<c\]
  done clear
  D)
  \[a=b=c\]
  done clear
  View Answer play_arrow

• question_answer11) The magnetic field in a travelling electromagnetic wave has a peak value of 20 \[nT\]. The peak value of electric field strength is:                                             [JEE MAIN 2013]
  A)
  \[\frac{3V}{m}\]        
  done clear
  B)
  \[\frac{6V}{m}\]
  done clear
  C)
  \[\frac{9V}{m}\]        
  done clear
  D)
  \[\frac{12V}{m}\]
  done clear
  View Answer play_arrow

• question_answer12) Photons of an electromagnetic radiation has an energy 11 keV each. To which region of electromagnetic spectrum does it belong?                                  [JEE ONLINE 09-04-2013]
  A)
  X-ray region
  done clear
  B)
  Ultra violet region
  done clear
  C)
              Infrared region
  done clear
  D)
  Visible region  
  done clear
  View Answer play_arrow

• question_answer13) A plane electromagnetic wave in a non-magnetic dielectric medium is given by \[\overset{\to }{\mathop{\operatorname{E}}}\,={{\overset{\to }{\mathop{\operatorname{E}}}\,}_{0}}\]\[(4\times {{10}^{-7}}x-50t)\] with distance being in meter and time in seconds. The dielectric constant of the medium is:      [JEE ONLINE 22-04-2013]
  A)
  2.4
  done clear
  B)
  5.8
  done clear
  C)
  8.2
  done clear
  D)
  4.8
  done clear
  View Answer play_arrow

• question_answer14) Select the correct statement form the following:                    [JEE ONLINE 23-04-2013]
  A)
  Electromagnetic waves cannot travel in vacuum
  done clear
  B)
              Electromagnetic waves are longitudinal waves 
  done clear
  C)
              Electromagnetic waves are produced by charge moving with uniform velocity.
  done clear
  D)
              Electromagnetic waves carry both energy and momentum as they processes through space.
  done clear
  View Answer play_arrow

• question_answer15) 

  Match List – I (Electromagnetic wave type) with List – II (Its association/application) and select the correct option from the choices given below the lists:         [JEE MAIN 2014]

  List –I List-II Infrared waves (i) To treat muscular strain Radio waves (ii) For broadcasting X-rays (iii) To detect fracture of bones Ultraviolet rays (iv) Absorbed by the ozone layer of the atmosphere

  A)
  A-(iii),  B-(ii),   C-(i),    D-(iv)
  done clear
  B)
  A-(i),    B-(ii),   C-(iii),  D-(iv)
  done clear
  C)
  A-(iv),  B-(iii),  C-(ii),   D-(i)
  done clear
  D)
  A-(i),    B-(ii),   C-(iv),  D-(iii)
  done clear
  View Answer play_arrow

• question_answer16) During the propagation of electromagnetic waves in a medium:                   [JEE MAIN 2014]
  A)
  Electric energy density is equal to the magnetic energy density.
  done clear
  B)
  Both electric and magnetic energy densities are zero.
  done clear
  C)
  Electric energy density is double of the magnetic energy density.
  done clear
  D)
  Electric energy density is half of the magnetic density.
  done clear
  View Answer play_arrow

• question_answer17) 

  Match List I (Wavelength range of electromagnetic spectrum) with List II (Method of production of these waves) and select the correct option from the options given below the lists.

  List I List II (1) 700 nm to 1 mn (i) Vibration of atoms and molecules. (2) 1 nm to 400 nm (ii) Inner shell electrons in atoms moving from one energy level to a lower level. (3)\[<{{10}^{-3}}nm\] (iii) Radioactive decay of the nucleus. (4) 1 mm to 0.1 m (iv) Magnetron valve.          [JEE ONLINE 09-04-2014]

  A)
  (1)-(iv), (2)-(iii), (3)-(ii), (4)-(i)
  done clear
  B)
  (1)-(iii), (2)-(iv), (3)-(i), (4)-(ii)
  done clear
  C)
  (1)-(ii), (2)-(iii), (3)-(iv), (4)-(i)
  done clear
  D)
  (1)-(i), (2)-(ii), (3)-(iii), (4)-(iv)
  done clear
  View Answer play_arrow

• question_answer18) An electromagnetic wave of frequency  \[1\times {{10}^{14}}\] hertz is propagating along z-axis. The amplitude of electric field is 4 V/m. If \[{{\varepsilon }_{0}}=8.8\times {{10}^{-12}}{{C}^{2}}/N-{{m}^{2}},\]then average energy density of electric field will be:          [JEE ONLINE 11-04-2014]
  A)
  \[35.2\times {{10}^{-10}}J/{{m}^{3}}\]
  done clear
  B)
  \[35.2\times {{10}^{-11}}J/{{m}^{3}}\]
  done clear
  C)
  \[35.2\times {{10}^{-12}}J/{{m}^{3}}\]
  done clear
  D)
  \[35.2\times {{10}^{-13}}J/{{m}^{3}}\]
  done clear
  View Answer play_arrow

• question_answer19) 

  Match the List-I (Phenomenon associated with electromagnetic radiation) with List-II (Part of electromagnetic spectrum) and select the correct code from the choices given below this lists:      [JEE ONLINE 11-04-2014]

  (I) Doublet of sodium Visible radiation (II) Wavelength corresponding to temperature associated with the isotropic radiation filling all space Microwave (III) Wavelength emitted by Atomic hydrogen in Interstellar space Short radio wave (IV) Wavelength of radiation arising from two close energy levels in hydrogen X-rays

  A)
  (I)-, (II)-, (III)-, (IV)-
  done clear
  B)
  (I)-, (II)-, (III)-, (IV)-
  done clear
  C)
  (I)-, (II)-, (III)-, (IV)-
  done clear
  D)
  (I)-, (II)-, (III)-, (IV)-
  done clear
  View Answer play_arrow

• question_answer20) A lamp emits monochromatic green light uniformly in all directions. The lamp is 3% efficient in converting electrical power to electromagnetic waves and consumes 100 W of power. The amplitude of the electric field associated with the electromagnetic radiation at a distance of 5 m from the lamp will be nearly:                              [JEE ONLINE 12-04-2014]
  A)
  1.34 V/m
  done clear
  B)
  2.68 V/m
  done clear
  C)
  4.02 V/m
  done clear
  D)
  5.36 V/m
  done clear
  View Answer play_arrow

• question_answer21) If microwaves, X rays, infrared, gamma rays, ultra-violet, radio waves and visible parts of the electromagnetic spectrum by are denoted M, X, I, G, U, R and V then which of the following is the arrangement in ascending order of wavelength? [JEE ONLINE 19-04-2014]
  A)
  R, M, I, V, U, X and G
  done clear
  B)
  M, R, V, X, U, G and I
  done clear
  C)
  G, X, U, V, I, M and R
  done clear
  D)
  I, M, R, U, V, X and G
  done clear
  View Answer play_arrow

• question_answer22) A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1m from the diode is:                                    [JEE MAIN 2015]
  A)
  5.48 V/m
  done clear
  B)
  7.75 V/m
  done clear
  C)
  1.73 V/m
  done clear
  D)
  2.45 V/mions /
  done clear
  View Answer play_arrow

• question_answer23) An electromagnetic wave travelling in the x-direction has frequency of \[2\times {{10}^{14}}Hz\]and electric field amplitude of \[27V{{m}^{-1}}.\]From the options given below, which one describes the magnetic field for this wave? [JEE ONLINE 10-04-2015]
  A)
  \[\overset{\to }{\mathop{B}}\,(x.t)=(9\times {{10}^{-8}}T)\hat{i}\]\[\sin \left[ 2\pi (1.5\times {{10}^{-8}}x-2\times {{10}^{14}}t) \right]\]
  done clear
  B)
  \[\overset{\to }{\mathop{B}}\,(x,t)=(3\times {{10}^{-8}}T)\hat{j}\] \[\sin \left[ 1.5\times {{10}^{-6}}x-2\times {{10}^{14}}t) \right]\]
  done clear
  C)
  \[\overset{\to }{\mathop{B}}\,(x,t)=(3\times {{10}^{-8}}T)\hat{j}\]\[\sin \left[ 2\pi (1.5\times {{10}^{-8}}x-2\times {{10}^{14}}t) \right]\]
  done clear
  D)
  None of these
  done clear
  View Answer play_arrow

• question_answer24) For plane electromagnetic waves propagating in the z direction, which one of the following combination gives the correct possible direction for \[\overset{\to }{\mathop{E}}\,\]and \[\overset{\to }{\mathop{B}}\,\]field respectively? [JEE MAIN 11-04-2015]
  A)
  \[\left( \hat{i}+2\hat{j} \right)\]and\[\left( 2\hat{i}-\hat{j} \right)\]
  done clear
  B)
  \[\left( -2\hat{i}-3\hat{j} \right)\]and\[\left( 3\hat{i}-2\hat{j} \right)\]
  done clear
  C)
  \[\left( 2\hat{i}+3\hat{j} \right)\]and\[\left( \hat{i}+2\hat{j} \right)\]
  done clear
  D)
  \[\left( 3\hat{i}+4\hat{j} \right)\]and\[\left( 4\hat{i}-3\hat{j} \right)\]
  done clear
  View Answer play_arrow

• question_answer25) 

  Arrange the following electromagnetic radiations per quantum in the order of increasing energy :-      [JEE MAIN - I 3-4-2016]

  A : Blue light                B : Yellow light

  C : X–ray                     D : Radio wave

  A)
  B, A, D, C
  done clear
  B)
  D, B, A, C
  done clear
  C)
  A, B, D, C
  done clear
  D)
  C, A, B, D
  done clear
  View Answer play_arrow

• question_answer26) Microwave oven acts on the principle of:                             [JEE ONLINE 09-04-2016]
  A)
  giving rotational energy to water molecules
  done clear
  B)
  giving vibrational energy to water molecules
  done clear
  C)
  giving translational energy to water molecules
  done clear
  D)
  transferring electrons from lower to higher energy levels in water molecule
  done clear
  View Answer play_arrow

• question_answer27) Consider an electromagnetic wave propagating in vacuum. Choose the correct statement:            [JEE ONLINE 10-04-2016]
  A)
  For an electromagnetic wave propagating in +y direction the electric field is \[\overrightarrow{E}=\frac{1}{\sqrt{2}}{{E}_{yz}}\left( x,t \right)\hat{z}\]and the magnetic field is \[\overrightarrow{B}=\frac{1}{\sqrt{2}}{{B}_{z}}\left( x,t \right)\hat{y}\]
  done clear
  B)
              For an electromagnetic wave propagating in +y direction the electric field is \[\overrightarrow{E}=\frac{1}{\sqrt{2}}{{E}_{yz}}\left( x,t \right)\hat{y}\]and he magnetic field is \[\overrightarrow{B}=\frac{1}{\sqrt{2}}{{B}_{yz}}\left( x,t \right)\hat{z}\]
  done clear
  C)
              For an electromagnetic wave propagating in +x direction the electric field is             \[\overrightarrow{E}=\frac{1}{\sqrt{2}}{{E}_{yz}}\left( y,z,t \right)\left( \hat{y}+\hat{z} \right)\] and the magnetic field is \[\overrightarrow{B}=\frac{1}{\sqrt{2}}{{B}_{yz}}\left( y,z,t \right)\left( \hat{y}+\hat{z} \right)\]
  done clear
  D)
              For an electromagnetic wave propagating in +x direction the electric field is \[\overrightarrow{E}=\frac{1}{\sqrt{2}}{{E}_{yz}}\left( x,t \right)\left( \hat{y}-\hat{z} \right)\] and eh magnetic field is \[B=\frac{1}{\sqrt{2}}{{B}_{yz}}\left( x,t \right)\left( \hat{y}+\hat{z} \right)\]
  done clear
  View Answer play_arrow

• question_answer28) Magnetic field in a plane electromagnetic wave is given by\[\vec{B}={{B}_{0}}\sin (kx+\omega t)\hat{j}T\] Expression for corresponding electric field will be                    [JEE Online 08-04-2017]
  A)
  \[\vec{E}=-{{B}_{0}}c\sin (kx+\omega t)\hat{k}V/m\]
  done clear
  B)
  \[\vec{E}={{B}_{0}}c\sin (kx-\omega t)\hat{k}V/m\]
  done clear
  C)
  \[\vec{E}={{B}_{0}}c\sin (kx+\omega t)\hat{k}V/m\]
  done clear
  D)
  \[\vec{E}=\frac{{{B}_{0}}}{c}\sin \,(kx+\omega t)\hat{k}V/m\]
  done clear
  View Answer play_arrow

• question_answer29) The electric field component of a monochromatic radiation is given by \[\vec{E}=2{{E}_{0}}\hat{i}\,\cos kz\,\cos \omega t\] Its magnetic field \[\vec{B}\]  [JEE Online 09-04-2017]
  A)
  \[\frac{2{{E}_{0}}}{c}\hat{j}\,\sin kz\,\sin \omega t\]
  done clear
  B)
  \[\frac{2{{E}_{0}}}{c}\hat{j}\cos kz\,\cos \omega t\]
  done clear
  C)
  \[\frac{2{{E}_{0}}}{c}\hat{j}\sin kz\,\cos \omega t\]
  done clear
  D)
  \[-\frac{2{{E}_{0}}}{c}\hat{j}\sin kz\,\sin \omega t\]
  done clear
  View Answer play_arrow

• question_answer30) An EM wave from air enters a medium. The electric fields are \[{{\overset{\to }{\mathop{\text{E}}}\,}_{1}}={{E}_{01}}\,\,\widehat{x}\cos \left[ 2\pi v\left( \frac{z}{c}-t \right) \right]\] in air and \[{{\overset{\to }{\mathop{\text{E}}}\,}_{2}}={{E}_{02}}\,\,\widehat{x}\cos [k(2z-ct)]\] in medium, where the wave number \[k\] and frequency \[v\] refer to their values in air. The medium is non-magnetic. If \[{{\in }_{{{r}_{1}}}}\] and \[{{\in }_{{{r}_{2}}}}\]refer to relative permittivity’s of air and medium respectively, which of the following options is correct? [JEE Main Online 08-04-2018]
  A)
  \[\frac{{{\in }_{{{r}_{1}}}}}{{{\in }_{{{r}_{2}}}}}=\frac{1}{4}\]
  done clear
  B)
  \[\frac{{{\in }_{{{r}_{1}}}}}{{{\in }_{{{r}_{2}}}}}=\frac{1}{2}\]
  done clear
  C)
  \[\frac{{{\in }_{{{r}_{1}}}}}{{{\in }_{{{r}_{2}}}}}=4\]
  done clear
  D)
  \[\frac{{{\in }_{{{r}_{1}}}}}{{{\in }_{{{r}_{2}}}}}=2\]
  done clear
  View Answer play_arrow

• question_answer31) A monochromatic beam of light has a frequency \[v=\frac{3}{2\pi }\times {{10}^{12}}Hz\] and is propagating along the direction\[\frac{\widehat{i}+\widehat{j}}{\sqrt{2}}\]. It is polarized along \[\widehat{k}\] the direction. The acceptable form for the magnetic field is: [JEE Online 15-04-2018]
  A)
  \[k\frac{{{E}_{0}}}{C}\left( \frac{\widehat{i}-\widehat{j}}{\sqrt{2}} \right)\cos \left[ {{10}^{4}}\left( \frac{\widehat{i}-\widehat{j}}{\sqrt{2}} \right).\overrightarrow{r}-(3\times {{10}^{12}})t \right]\]
  done clear
  B)
  \[\frac{{{E}_{0}}}{C}\left( \frac{\widehat{i}-\widehat{j}}{\sqrt{2}} \right)\cos \left[ {{10}^{4}}\left( \frac{\widehat{i}+\widehat{j}}{\sqrt{2}} \right).\overrightarrow{r}-(3\times {{10}^{12}})t \right]\]
  done clear
  C)
  \[\frac{{{E}_{0}}}{C}\widehat{k}\cos \left[ {{10}^{4}}\left( \frac{\widehat{i}+\widehat{j}}{\sqrt{2}} \right).\overrightarrow{r}+(3\times {{10}^{12}})t \right]\]
  done clear
  D)
  \[\frac{{{E}_{0}}}{C}\frac{\left( \widehat{i}+\widehat{j}+\widehat{k} \right)}{\sqrt{3}}\cos \left[ {{10}^{4}}\left( \frac{\widehat{i}+\widehat{j}}{\sqrt{2}} \right).\overrightarrow{r}+(3\times {{10}^{12}})t \right]\]
  done clear
  View Answer play_arrow

• question_answer32) A plane polarized monochromatic EM wave is travelling a vacuum along z direction such that at \[t={{t}_{1}}\] it is found that the electric field is zero at a spatial point \[{{z}_{1}}\]. The next zero that occurs in its neighbourhood is at \[{{z}_{2}}\]. The frequency of the electromagnetic wave is: [JEE Online 15-04-2018 (II)]
  A)
  \[\frac{3\times {{10}^{8}}}{|{{z}_{2}}-{{z}_{1}}|}\]
  done clear
  B)
  \[\frac{6\times {{10}^{8}}}{|{{z}_{2}}-{{z}_{1}}|}\]
  done clear
  C)
  \[\frac{1.5\times {{10}^{8}}}{|{{z}_{2}}-{{z}_{1}}|}\]
  done clear
  D)
  \[\frac{1}{{{t}_{1}}+\frac{|{{z}_{2}}-{{z}_{1}}|}{3\times {{10}^{8}}}}\]
  done clear
  View Answer play_arrow

• question_answer33) A plane electromagnetic wave of wavelength\[\lambda \] has an intensity \[I.\] It is propagating along the positive\[Y-direction.\] The allowed expressions for the electric and magnetic fields are given by
  A)
  \[\vec{E}=\sqrt{\frac{I}{{{\varepsilon }_{0}}C}}\cos \left[ \frac{2\pi }{\lambda }(y-ct) \right]\hat{i};\vec{B}=\frac{1}{c}E\hat{k}\]
  done clear
  B)
  \[\vec{E}=\sqrt{\frac{I}{{{\varepsilon }_{0}}C}}\cos \left[ \frac{2\pi }{\lambda }(y-ct) \right]\hat{k};\vec{B}=-\frac{1}{c}E\hat{i}\]
  done clear
  C)
  \[\vec{E}=\sqrt{\frac{2I}{{{\varepsilon }_{0}}C}}\cos \left[ \frac{2\pi }{\lambda }(y-ct) \right]\hat{k};\vec{B}=+\frac{1}{c}E\hat{i}\]
  done clear
  D)
  \[\vec{E}=\sqrt{\frac{2I}{{{\varepsilon }_{0}}C}}\cos \left[ \frac{2\pi }{\lambda }(y+ct) \right]\hat{k};\vec{B}=\frac{1}{c}E\hat{i}\]
  done clear
  View Answer play_arrow

• question_answer34) A plane electromagnetic wave of frequency 50 MHz travels in free space along the positive x-direction. At a particular point in space and time,\[\overrightarrow{E}=6.3\text{ }\overrightarrow{j}\text{ }V/m\]. The corresponding magnetic field B, at that point will be- [JEE Main 09-Jan-2019 Morning]
  A)
        \[18.9\times {{10}^{-8}}\text{ }\widehat{k}T\]
  done clear
  B)
  \[2.1\times {{10}^{-8}}\text{ }\widehat{k}T\]
  done clear
  C)
  \[18.9\times {{10}^{8}}\text{ }\widehat{k}T\]
  done clear
  D)
  \[6.3\times {{10}^{-8}}\text{ }\widehat{k}T\]
  done clear
  View Answer play_arrow

• question_answer35) The energy associated with electric field is (\[{{U}_{E}}\]) and with magnetic field is (\[{{U}_{B}}\]) for an electromagnetic wave in free space. Then: [JEE Main 09-Jan-2019 Evening]
  A)
  \[{{U}_{E}}<{{U}_{B}}\]
  done clear
  B)
  \[{{U}_{E}}=\,\frac{{{U}_{B}}}{2}\]
  done clear
  C)
  \[{{U}_{E}}={{U}_{B}}\]
  done clear
  D)
  \[{{U}_{E}}>{{U}_{B}}\]
  done clear
  View Answer play_arrow

• question_answer36) If the magnetic field of a plane electromagnetic wave is given by (the speed of light \[=~\,3~\times ~{{10}^{8}}m/s)\] \[B\,=\,100\times {{10}^{-6}}\,\sin \,\left[ 2\pi \times 2\times {{10}^{15}}\left( t-\frac{x}{c} \right) \right]\]then the maximum electric field associated with it is – [JEE Main 10-Jan-2019 Morning]
  A)
  \[4.5\times {{10}^{4}}\,N/C\]
  done clear
  B)
  \[4\times {{10}^{4}}\,N/C\]
  done clear
  C)
  \[6\times {{10}^{4}}\,N/C\]
  done clear
  D)
  \[3\times {{10}^{4}}\,N/C\]
  done clear
  View Answer play_arrow

• question_answer37) The electric field of a plane polarized electromagnetic wave in free space at time  \[t=0\] is given by an expression \[\overrightarrow{E}\left( x,y \right)=10\widehat{j}\text{ }cos\left[ \left( 6x+8z \right) \right]\]. The magnetic field \[\overrightarrow{B}\left( x,\text{ }z,\text{ }t \right)\] is given by - (c is the velocity of light) [JEE Main 10-Jan-2019 Evening]
  A)
  \[\frac{1}{c}(6\widehat{k}+8\widehat{i})\,cos[(6x+8z-10ct)]\]
  done clear
  B)
  \[\frac{1}{c}(6\widehat{k}-8\widehat{i})\,cos[(6x+8z-10ct)]\]
  done clear
  C)
  \[\frac{1}{c}(6\widehat{k}+8\widehat{i})\,cos[(6x-8z+10ct)]\]
  done clear
  D)
  \[\frac{1}{c}(6\widehat{k}-8\widehat{i})\,cos[(6x+8z+10ct)]\]
  done clear
  View Answer play_arrow

• question_answer38) A 27 mW laser beam has a cross-sectional area of\[10\text{ }m{{m}^{2}}\]. The magnitude of the maximum electric field in this electromagnetic wave is given by [Given permittivity of space\[{{\varepsilon }_{0}}=9\times {{10}^{-12}}\] SI units, speed of light \[c=3\times {{10}^{8}}m/s\]] [JEE Main 11-Jan-2019 Evening]
  A)
  2 kV/m
  done clear
  B)
  0.7 kV/m
  done clear
  C)
  1 kV/m
  done clear
  D)
  1.4 kV/m
  done clear
  View Answer play_arrow

• question_answer39) The mean intensity of radiation on the surface of the Sun is about \[{{10}^{8}}W/{{m}^{2}}\]. The rms value of the corresponding magnetic field is closest to [JEE Main 12-Jan-2019 Evening]
  A)
  \[{{10}^{-2}}T\]
  done clear
  B)
  \[1T\]
  done clear
  C)
  \[{{10}^{-4}}T\]
  done clear
  D)
  \[{{10}^{2}}T\]
  done clear
  View Answer play_arrow

• question_answer40) 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 \[E=6V{{m}^{-1}}\] along y-direction. Its corresponding magnetic field component, B would be :      [JEE Main 8-4-2019 Morning]
  A)
  \[6\times {{10}^{-8}}T\] along z-direction
  done clear
  B)
  \[6\times {{10}^{-8}}T\] along x-direction
  done clear
  C)
  \[2\times {{10}^{-8}}T\] along z-direction
  done clear
  D)
  \[2\times {{10}^{-8}}T\] along y-direction
  done clear
  View Answer play_arrow

• question_answer41) A circuit connected to an ac source of emf \[e={{e}_{0}}\sin (100t)\]with t in seconds, gives a phase difference of\[\frac{\pi }{4}\] between the emf e and current i. Which of the following circuits will exhibit this? [JEE Main 8-4-2019 Afternoon]
  A)
  RC circuit with \[R=1k\Omega \]and \[C=1\mu F\]
  done clear
  B)
  RL circuit with \[R=1k\Omega \] and L = 1mH
  done clear
  C)
  RL circuit with \[R=1k\Omega \] and L = 10 mH
  done clear
  D)
  RC circuit with \[R=1k\Omega \] and \[C=10\mu F\]
  done clear
  View Answer play_arrow

• question_answer42) The magnetic field of an electromagnetic wave is given by :- \[\vec{B}=1.6\times {{10}^{-6}}\cos \left( 2\times {{10}^{7}}z+6\times {{10}^{15}}t \right)\left( 2\hat{i}+\hat{j} \right)\frac{Wb}{{{m}^{2}}}\]The associated electric field will be :-             [JEE Main 8-4-2019 Afternoon]
  A)
  \[\vec{E}=4.8\times {{10}^{2}}\cos \left( 2\times {{10}^{7}}z+6\times {{10}^{15}}t \right)\left( \hat{i}-2\hat{j} \right)\frac{V}{m}\]
  done clear
  B)
  \[\vec{E}=4.8\times {{10}^{2}}\cos \left( 2\times {{10}^{7}}z-6\times {{10}^{15}}t \right)\left( 2\hat{i}+\hat{j} \right)\frac{V}{m}\]
  done clear
  C)
  \[\vec{E}=4.8\times {{10}^{2}}\cos \left( 2\times {{10}^{7}}z-6\times {{10}^{15}}t \right)\left( -2\hat{j}+\hat{i} \right)\frac{V}{m}\]
  done clear
  D)
  \[\vec{E}=4.8\times {{10}^{2}}\cos \left( 2\times {{10}^{7}}z+6\times {{10}^{15}}t \right)\left( -\hat{i}+2\hat{j} \right)\frac{V}{m}\]
  done clear
  View Answer play_arrow

• question_answer43) The electric field of light wave is given as \[\vec{E}={{10}^{-3}}\cos \left( \frac{2\pi x}{5\times {{10}^{-7}}}-2\pi \times 6\times {{10}^{14}}t \right)\]\[\hat{x}\frac{N}{C}.\]This light falls on a metal plate of work function 2eV. The stopping potential of the photo-electrons is : Given, E (in eV) \[=\frac{12375}{\lambda (in{\AA})}\]      [JEE Main 9-4-2019 Morning]
  A)
  0.48 V
  done clear
  B)
  2.0 V
  done clear
  C)
  2.48 V
  done clear
  D)
  0.72 V
  done clear
  View Answer play_arrow

• question_answer44) 

  The magnetic field of a plane electromagnetic wave is given by :

  \[\vec{B}={{B}_{0}}\hat{i}[cos(kz-\omega t)]+{{B}_{1}}\hat{j}\cos (kz+\omega t)\] where \[{{B}_{0}}=3\times {{10}^{-5}}T\] and \[{{B}_{1}}=2\times {{10}^{-6}}T.\] The rms  value of the force experienced by a stationary charge \[Q={{10}^{-4}}C\]at \[z=0\]is closest to :         [JEE Main 9-4-2019 Morning]

  A)
        \[0.9\text{ }N\]
  done clear
  B)
  \[0.1\text{ }N\]
  done clear
  C)
  \[3\times {{10}^{2}}N\]
  done clear
  D)
  \[0.6N\]
  done clear
  View Answer play_arrow

• question_answer45) 

  The electric field of a plane electromagnetic wave is given by \[\vec{E}={{E}_{0}}\hat{i}\cos (kz)cos(\omega t)\]

  The corresponding magnetic field \[\vec{B}\]is then given by:      [JEE Main 10-4-2019 Morning]

  A)
  \[\vec{B}=\frac{{{E}_{0}}}{C}\hat{j}\sin (kz)cos(\omega t)\]
  done clear
  B)
  \[\vec{B}=\frac{{{E}_{0}}}{C}\hat{j}\sin (kz)sin(\omega t)\]
  done clear
  C)
  \[\vec{B}=\frac{{{E}_{0}}}{C}\hat{k}\sin (kz)cos(\omega t)\]
  done clear
  D)
  \[\vec{B}=\frac{{{E}_{0}}}{C}\hat{j}\sin (kz)sin(\omega t)\]
  done clear
  View Answer play_arrow

• question_answer46) The correct figure that shows, schematically, the wave pattern produced by superposition of two waves of frequencies 9 Hz and 11 Hz is : [JEE Main 10-4-2019 Afternoon]
  A)
  
  done clear
  B)
  
  done clear
  C)
  
  done clear
  D)
  
  done clear
  View Answer play_arrow

• question_answer47) 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 propagation \[\hat{s},\] is: [JEE Main Held on 12-4-2019 Morning]
  A)
  \[\hat{s}=\frac{4\hat{j}-3\hat{k}}{5}\]
  done clear
  B)
  \[\hat{s}=\frac{3\hat{j}-4\hat{j}}{5}\]
  done clear
  C)
  \[\hat{s}=\left( \frac{-3\hat{j}+4\hat{k}}{5} \right)\]
  done clear
  D)
  \[\hat{s}=\frac{-4\hat{j}+3\hat{j}}{5}\]
  done clear
  View Answer play_arrow

• question_answer48) 

  Consider the LR circuit shown in the figure. If the switch S is closed at t = 0 then the amount of charge that passes through the battery between t = 0 and \[t=\frac{L}{R}\]is [JEE Main 12-4-2019 Afternoon]

  A)
  \[\frac{EL}{7.3{{R}^{2}}}\]
  done clear
  B)
  \[\frac{EL}{2.7{{R}^{2}}}\]
  done clear
  C)
  \[\frac{7.3EL}{{{R}^{2}}}\]
  done clear
  D)
  \[\frac{2.7EL}{{{R}^{2}}}\]
  done clear
  View Answer play_arrow

• question_answer49) A plane electromagnetic wave having a frequency v = 23.9 GHz propagates along the positive z-direction in free space. The peak value of the electric field is 60 V/m. Which among the following is the acceptable magnetic field component in the electromagnetic wave? [JEE Main 12-4-2019 Afternoon]
  A)
  \[\vec{B}=2\times {{10}^{7}}\sin (0.5\times {{10}^{3}}z+1.5\times {{10}^{11}}t)\hat{i}\]
  done clear
  B)
  \[\vec{B}=2\times {{10}^{-7}}\sin (1.5\times {{10}^{2}}x+0.5\times {{10}^{11}}t)\hat{j}\]
  done clear
  C)
  \[\vec{B}=2\times {{10}^{-7}}\sin (0.5\times {{10}^{3}}z-1.5\times {{10}^{11}}t)\hat{i}\]
  done clear
  D)
  \[\vec{B}=60\sin (0.5\times {{10}^{3}}x+1.5\times {{10}^{11}}t)\hat{k}\]
  done clear
  View Answer play_arrow

• question_answer50) If the magnetic field in a plane electromagnetic wave is given by \[\overline{B}=3\times {{10}^{-8}}\sin (1.6\times {{10}^{3}}x+48\times {{10}^{10}}t)\hat{j}T\], then what will be expression for electric field? [JEE MAIN Held on 07-01-2020 Morning]
  A)
  \[\vec{E}=\left( 60\sin (1.6\times {{10}^{3}}x+48\times {{10}^{10}}t)\hat{k}V/m \right)\]
  done clear
  B)
  \[\vec{E}=\left( 3\times {{10}^{-8}}\sin (1.6\times {{10}^{3}}x+48\times {{10}^{10}}t)\hat{i}V/m \right)\]
  done clear
  C)
  \[\vec{E}=\left( 9\sin (1.6\times {{10}^{3}}x+48\times {{10}^{10}}t)\hat{k}V/m \right)\]
  done clear
  D)
  \[\vec{E}=\left( 3\times {{10}^{-8}}sin(1.6\times {{10}^{3}}x+48\times {{10}^{10}}t)\hat{j}V/m \right)\]
  done clear
  View Answer play_arrow

• question_answer51) 

  The electric field of a plane electromagnetic wave is given by \[\vec{E}={{E}_{0}}\frac{\hat{i}+\hat{j}}{\sqrt{2}}\,\cos \,(kz+\omega t)\]

  At t = 0, a positively charged particle is at the point \[(x,y,z)\,=\,\left( 0,0,\,\frac{\pi }{k} \right)\].

  If its instantaneous velocity at (t = 0) is\[{{v}_{0}}\,\hat{k},\], the force acting on it due to the wave is: [JEE MAIN Held on 07-01-2020 Evening]

  A)
  Antiparallel to \[\frac{\hat{i}+\hat{j}}{\sqrt{2}}\]
  done clear
  B)
  Zero
  done clear
  C)
  Parallel to \[\frac{\hat{i}+\hat{j}}{\sqrt{2}}\]
  done clear
  D)
  Parallel to \[\hat{k}\]
  done clear
  View Answer play_arrow

• question_answer52) The critical angle of medium for a specific wavelength, if the medium has relative permittivity 3 and relative permeability\[\frac{4}{3}\] for this wavelength, will be [JEE MAIN Held On 08-01-2020 Morning]
  A)
  \[60{}^\circ \]
  done clear
  B)
  \[45{}^\circ \]
  done clear
  C)
  \[15{}^\circ \]
  done clear
  D)
  \[30{}^\circ \]
  done clear
  View Answer play_arrow

• question_answer53) 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\[\vec{B}=5\times {{10}^{-8}}\hat{j}\text{ }T\]. The corresponding electric field \[\vec{E}\] is (speed of light \[c=3\times {{10}^{8}}\text{ }m{{s}^{1}}\])  [JEE MAIN Held on 08-01-2020 Evening]
  A)
  \[-1.66\times {{10}^{-16}}\hat{i}\text{ }V/m\]
  done clear
  B)
  \[1.66\times {{10}^{-16}}\hat{i}\text{ }V/m\]
  done clear
  C)
  \[-15\text{ \hat{i} }V/m\]
  done clear
  D)
  \[15\,\,\hat{i}\,\,V/m\]
  done clear
  View Answer play_arrow

• question_answer54) 

  The electric fields of two plane electromagnetic plane waves in vacuum are given by

  \[{{\vec{E}}_{1}}={{E}_{0}}\hat{j}\cos \left( \omega t-kx \right)\]

  and       \[{{\vec{E}}_{2}}={{E}_{0}}\hat{k}\cos \left( \omega t-ky \right)\]

  At t = 0, a particle of chcarge q is at origin with a velocity \[\vec{v}=0.8c\hat{j}\] (c is the speed of light in vaccum). The instantaneous force experienced by the particle is: [JEE MAIN Held on 09-01-2020 Morning]

  A)
              \[{{E}_{0}}q\left( 0.4\hat{i}-3\hat{j}+0.8\hat{k} \right)\]
  done clear
  B)
              \[{{E}_{0}}q\left( -\,0.8\hat{i}+\hat{j}+\hat{k} \right)\]
  done clear
  C)
              \[{{E}_{0}}q\left( 0.8\hat{i}+\hat{j}+0.2\hat{k} \right)\]
  done clear
  D)
              \[{{E}_{0}}q\left( 0.8\hat{i}-\hat{j}+0.4\hat{k} \right)\]
  done clear
  View Answer play_arrow

• question_answer55) A plane electromagnetic wave is propagating along the direction \[\frac{\hat{i}+\hat{j}}{\sqrt{2}}\], with its polarization along the direction \[\hat{k}\]. The correct form of the magnetic field of the wave would be (here \[{{B}_{0}}\]is an appropriate constant) [JEE MAIN Held on 09-01-2020 Evening]
  A)
  \[{{B}_{0}}\frac{\hat{i}-\hat{j}}{\sqrt{2}}\cos \left( \omega t-k\frac{\hat{i}+\hat{j}}{\sqrt{2}} \right)\]
  done clear
  B)
  \[{{B}_{0}}\hat{k}\cos \left( \omega t-k\frac{\hat{i}+\hat{j}}{\sqrt{2}} \right)\]
  done clear
  C)
  \[{{B}_{0}}\frac{\hat{i}+\hat{j}}{\sqrt{2}}\cos \left( \omega t-k\frac{\hat{i}+\hat{j}}{\sqrt{2}} \right)\]
  done clear
  D)
  \[{{B}_{0}}\frac{\hat{j}-\hat{i}}{\sqrt{2}}\cos \left( \omega t+k\frac{\hat{i}+\hat{j}}{\sqrt{2}} \right)\]
  done clear
  View Answer play_arrow