JEE Main & Advanced Physics EM Waves Question Bank

done Self Evaluation Test - Electromagnetic Waves Total Questions - 70

• question_answer1)
  The magnetic field in the plane electromagnetic field is given by: \[{{B}_{y}}=2\times {{10}^{-7}}\sin (0.5\times {{10}^{3}}z+1.5\times {{10}^{11}}t)T\] The expression for the electric field may be given by
  A)
  \[{{E}_{y}}=2\times {{10}^{-7}}\sin (0.5\times {{10}^{3}}z+1.5\times {{10}^{11}}t)V/m\] done clear
  B)
  \[{{E}_{x}}=2\times {{10}^{-7}}\sin (0.5\times {{10}^{3}}z+1.5\times {{10}^{11}}t)V/m\] done clear
  C)
  \[{{E}_{y}}=60\sin (0.5\times {{10}^{3}}z+1.5\times {{10}^{11}}t)V/m\] done clear
  D)
  \[{{E}_{x}}=60\sin (0.5\times {{10}^{3}}z+1.5\times {{10}^{11}}t)V/m\] done clear
  View Solution play_arrow

• question_answer2)
  The figure shows graphs of the electric field magnitude E versus time t for four uniform electric fields, all contained within identical circular regions. Which of them is according to the magnitudes of the magnetic field?
  A)
  A  done clear
  B)
  B      done clear
  C)
  C done clear
  D)
  D done clear
  View Solution play_arrow

• question_answer3)
  In an apparatus, the electric field was found to oscillate with an amplitude of\[24\text{ }V/m\]. The magnitude of the oscillating magnetic field will be
  A)
  \[6\times {{10}^{-6}}T\] done clear
  B)
  \[2\times {{10}^{-8}}T\] done clear
  C)
  \[8\times {{10}^{-8}}T\] done clear
  D)
  \[12\times {{10}^{-6}}T\] done clear
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• question_answer4)
  A circular ring of radius r is placed in a homogeneous magnetic field perpendicular to the plane of the ring. The field B changes with time according to equation \[B=kt,\]where, k is a constant and t is the time). The electric field in the ring is:               
  A)
  \[\frac{kr}{4}\] done clear
  B)
  \[\frac{kr}{3}\]    done clear
  C)
  \[\frac{kr}{2}\] done clear
  D)
  \[\frac{k}{2r}\] done clear
  View Solution play_arrow

• question_answer5)
  The rms value of the electric field of the light coming from the Sun is\[720\text{ }N/C\]. The average total energy density of the electromagnetic wave is
  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 Solution play_arrow

• question_answer6)
  For plane electromagnetic waves propagating in the z-direction, which one of the following combination gives the correct possible direction for \[\vec{E}\] and \[\vec{B}\] field respectively?
  A)
  \[(2\hat{i}+3\hat{j})\] and \[(\hat{i}+2\hat{j})\] done clear
  B)
  \[(-2\hat{i}-3\hat{j})\] and \[(3\hat{i}-2\hat{j})\] done clear
  C)
  \[(3\hat{i}+4\hat{j})\] and \[(4\hat{i}-3\hat{j})\] done clear
  D)
  \[(\hat{i}+2\hat{j})\] and \[(2\hat{i}-\hat{j})\] done clear
  View Solution play_arrow

• question_answer7)
  A plane electromagnetic wave propagating in the X-direction has wavelength of\[6.0\text{ }mm\]. The electric field is in the Y-direction and its maximum magnitude is\[33\text{ }V{{m}^{-1}}\]. The equation for the electric field as a function of x and t is
  A)
  \[11\,\sin \pi \left( t-\frac{x}{c} \right)\] done clear
  B)
         \[33\sin \left[ \pi \times {{10}^{11}}\left( t-\frac{x}{c} \right) \right]\] done clear
  C)
  \[33\sin \,\pi \left( t-\frac{x}{c} \right)\] done clear
  D)
  \[11\sin \,\left[ \pi \times {{10}^{11}}\left( t-\frac{x}{c} \right) \right]\] done clear
  View Solution play_arrow

• question_answer8)
  A new system of unit is evolved in which the values of \[{{\mu }_{0}}\] and \[{{\in }_{0}}\] are 2 and 8 respectively. Then the speed of light in this system will be
  A)
  \[0.25\]  done clear
  B)
  \[0.5\]    done clear
  C)
  \[0.75\]   done clear
  D)
  \[1\] done clear
  View Solution play_arrow

• question_answer9)
  An electromagnetic wave of frequency \[1\times {{10}^{14}}\]hertz is propagating along z-axis. The amplitude of electric field is\[4\text{ }V/m\]. If \[{{\varepsilon }_{0}}=8.8\times {{10}^{-12}}{{C}^{2}}/N-{{m}^{2}},\] then average energy density of electric field will be:                        
  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 Solution play_arrow

• question_answer10)
  In an electromagnetic wave, the electric and magnetic fields are \[100\,V{{m}^{-1}}\] and \[0.265\,A\,{{m}^{-1}}\]. The maximum energy flow is
  A)
  \[26.5\text{ }W/{{m}^{2}}\]       done clear
  B)
         \[36.5\text{ }W/{{m}^{2}}\] done clear
  C)
  \[46.7\text{ }W/{{m}^{2}}\]       done clear
  D)
         \[765\text{ }W/{{m}^{2}}\] done clear
  View Solution play_arrow

• question_answer11)
  If \[{{\varepsilon }_{0}}\] and \[{{\mu }_{0}}\] are the electric permittivity and magnetic permeability in vacuum, \[\varepsilon \] and \[\mu \] are corresponding quantities in medium, then refractive index of the medium is
  A)
  \[\sqrt{\frac{\varepsilon }{{{\varepsilon }_{0}}}}\]   done clear
  B)
  \[\sqrt{\frac{{{\varepsilon }_{0}}\mu }{\varepsilon {{\mu }_{0}}}}\] done clear
  C)
  \[\sqrt{\frac{{{\varepsilon }_{0}}{{\mu }_{0}}}{\varepsilon \mu }}\] done clear
  D)
  \[\sqrt{\frac{\varepsilon \mu }{{{\varepsilon }_{0}}{{\mu }_{0}}}}\] done clear
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• question_answer12)
  For wave propagation of a \[10\text{ }MHz\] signal, what should be the maximum electron density in ionosphere
  A)
  \[\tilde{\ }1.2\times {{10}^{12}}{{m}^{-3}}\] done clear
  B)
  \[\tilde{\ }{{10}^{6}}{{m}^{-3}}\] done clear
  C)
  \[\tilde{\ }{{10}^{14}}{{m}^{-3}}\] done clear
  D)
  \[\tilde{\ }{{10}^{22}}{{m}^{-3}}\] done clear
  View Solution play_arrow

• question_answer13)
  A point source of electromagnetic radiation has an average power output of 800 W. The maximum value of electric field at a distance \[4.0\text{ }m\] from the source is                    
  A)
  \[64.7\text{ }V/m\]          done clear
  B)
  \[57.8\text{ }V/m\] done clear
  C)
  \[56.72\text{ }V/m\]        done clear
  D)
  \[54.77\text{ }V/m\] done clear
  View Solution play_arrow

• question_answer14)
  In a plane electromagnetic wave propagating in space has an electric field of amplitude \[9\times {{10}^{3}}V/m\] then the amplitude of the magnetic field is
  A)
  \[2.7\times {{10}^{12}}T\]        done clear
  B)
  \[9.0\times {{10}^{-3}}T\] done clear
  C)
  \[3.0\times {{10}^{-4}}T\]      done clear
  D)
         \[3.0\times {{10}^{-5}}T\] done clear
  View Solution play_arrow

• question_answer15)
  If c is the speed of electromagnetic waves in vacuum, its speed in a medium of dielectric constant K and relative permeability \[{{\mu }_{r}}\] is
  A)
  \[v=\frac{1}{\sqrt{{{\mu }_{r}}K}}\]                 done clear
  B)
  \[v=c\sqrt{{{\mu }_{r}}K}\] done clear
  C)
  \[v=\frac{c}{\sqrt{{{\mu }_{r}}K}}\]                  done clear
  D)
  \[v=\frac{K}{\sqrt{{{\mu }_{r}}C}}\] done clear
  View Solution play_arrow

• question_answer16)
  An electromagnetic wave with frequency cd 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)
  \[\overset{\to }{\mathop{E}}\,=-{{E}_{0}}\cos \left( \omega t+\frac{2\pi }{\lambda }y \right)\hat{x}\] 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 Solution play_arrow

• question_answer17)
  The magnetic field between the plates of radius 12 cm separated by distance of 4 mm of a parallel plate capacitor of capacitance \[100\text{ }pF\] along the axis of plates having conduction current of \[0.15A\] is
  A)
  zero done clear
  B)
  \[1.5\,T\] done clear
  C)
  \[15\,T\] done clear
  D)
  \[0.15\,T\] done clear
  View Solution play_arrow

• question_answer18)
  Consider an electromagnetic wave propagating in vacuum. Choose the correct statement:                  
  A)
  For an electromagnetic wave propagating in \[+y\] direction the electric field is \[\vec{E}=\frac{1}{\sqrt{2}}{{E}_{yz}}\,(x,t)\,\hat{z}\] and the magnetic field is \[\overrightarrow{B}=\frac{1}{\sqrt{2}}{{B}_{z}}(x,t)\hat{y}\] done clear
  B)
  For an electromagnetic wave propagating in \[+y\] direction the electric field is \[\vec{E}=\frac{1}{\sqrt{2}}{{E}_{yz}}(x,t)\,\hat{z}\] and the magnetic field is \[\vec{B}=\frac{1}{\sqrt{2}}{{B}_{yz}}(x,t)\,\hat{y}\] done clear
  C)
  For an electromagnetic wave propagating in \[+x\] direction the electric field is \[\vec{E}=\frac{1}{\sqrt{2}}{{E}_{yz}}\,(y,\,\,z,\,\,t)\]  \[\left( \hat{y}+\hat{z} \right)\] and the magnetic field is \[\vec{B}=\frac{1}{\sqrt{2}}{{B}_{yz}}\,(y,\,\,z,\,\,t)\,(\hat{y}+\hat{z})\] done clear
  D)
  For an electromagnetic wave propagating in \[+x\] direction the electric field is \[\vec{E}=\frac{1}{\sqrt{2}}{{E}_{yz}}\,(x,t)\,\left( \hat{y}-\hat{z} \right)\]and the magnetic field is \[\vec{B}=\frac{1}{\sqrt{2}}{{B}_{yz}}\,(x,t)\,\left( \hat{y}+\hat{z} \right)\] done clear
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• question_answer19)
  An electromagnetic wave of frequency \[v=3.0\text{ }MHz\] passes from vacuum into a dielectric medium with permittivity \[\in \,=4.0\]. Then
  A)
  wavelength is halved and frequency remains unchanged done clear
  B)
  wavelength is doubled and frequency becomes half done clear
  C)
  wavelength is doubled and the frequency remains unchanged done clear
  D)
  wavelength and frequency both remain unchanged. done clear
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• question_answer20)
  A plane electromagnetic wave is incident on a plane surface of area A, normally and is perfectly reflected. If energy E strikes the surface in time t then force exerted on the surface is (c =speed of light)
  A)
  \[\frac{2E}{Atc}\]          done clear
  B)
  \[\frac{E}{2c}\] done clear
  C)
  \[\frac{2E}{ct}\] done clear
  D)
  zero done clear
  View Solution play_arrow

• question_answer21)
  If a source is transmitting electromagnetic wave of frequency \[8.2\times {{10}^{6}}Hz,\] then wavelength of the electromagnetic waves transmitted from the source will be
  A)
  \[36.6\,m\] done clear
  B)
  \[40.5\,m\] done clear
  C)
  \[42.3\,m\] done clear
  D)
  \[50.9\,m\] done clear
  View Solution play_arrow

• question_answer22)
  In a wave \[{{E}_{0}}=100\,V{{m}^{-1}}\]. Find the magnitude of Pointing?s vector
  A)
  \[13.25\text{ }W{{m}^{-2}}\] done clear
  B)
  \[26.5\text{ }W{{m}^{-2}}\] done clear
  C)
  \[18.25\text{ }W{{m}^{-2}}\] done clear
  D)
  \[19.7\text{ }W{{m}^{-2}}\] done clear
  View Solution play_arrow

• question_answer23)
  The wave impendance of free space is
  A)
  zero                               done clear
  B)
  \[376.6\Omega \] done clear
  C)
  \[33.66\Omega \]          done clear
  D)
         \[3.76\Omega \] done clear
  View Solution play_arrow

• question_answer24)
  In an apparatus, the electric field was found to oscillate with an amplitude of\[18\text{ }V/m\]. The magnitude of the oscillating magnetic field will be
  A)
  \[4\times {{10}^{-6}}T\]           done clear
  B)
  \[6\times {{10}^{-8}}T\] done clear
  C)
  \[9\times {{10}^{-9}}T\]      done clear
  D)
         \[11\times {{10}^{-11}}T\] done clear
  View Solution play_arrow

• question_answer25)
  The average electric field of electromagnetic waves in certain region of free space is\[9\times {{10}^{-4}}N{{C}^{-1}}\]. Then the average magnetic field in the same region is of the order of
  A)
  \[27\times {{10}^{-4}}T\] done clear
  B)
  \[3\times {{10}^{-12}}T\] done clear
  C)
  \[\left( \frac{1}{3} \right)\times {{10}^{-12}}T\] done clear
  D)
  \[3\times {{10}^{-12}}T\] done clear
  View Solution play_arrow

• question_answer26)
  A plane electromagnetic wave travels in free space along X-direction. If the value of \[\vec{B}\] (in tesla) at a particular point in space and time is\[1.2\times {{10}^{-8}}\hat{k}\]. The value of \[\vec{E}\] (in \[V{{m}^{-1}}\]) at that point is
  A)
  \[1.\,2\text{ }\hat{j}\] done clear
  B)
  \[3.\,6\,\hat{k}\] done clear
  C)
  \[1.\,2\,\hat{k}\] done clear
  D)
  \[3.\,6\hat{j}\] done clear
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• question_answer27)
  A plane electromagnetic wave is incident on a material surface. If the wave delivers momentum p and energy E, then
  A)
  \[p=0,E=0\] done clear
  B)
  \[p\ne 0,E\ne 0\] done clear
  C)
  \[p\ne 0,E=0\] done clear
  D)
  \[p=0,E\ne 0\] done clear
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• question_answer28)
  In order to establish an instantaneous displacemet current of \[1\text{ }mA\] in the space between the plates of \[2\mu F\] parallel plate capacitor, the potential difference need to apply is    
  A)
  \[100\,\,V{{s}^{-1}}\]         done clear
  B)
         \[200\,\,V{{s}^{-1}}\] done clear
  C)
  \[300\,\,V{{s}^{-1}}\]        done clear
  D)
         \[500\,\,V{{s}^{-1}}\] done clear
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• question_answer29)
  In an electromagnetic wave, power is
  A)
  transmitted along the magnetic field done clear
  B)
  transmitted along the electric field equally done clear
  C)
  transferred along the electric and magnetic fields done clear
  D)
  transmitted in a direction perpendicular to both electric and magnetic fields done clear
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• question_answer30)
  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 B is then given by:
  A)
  \[\frac{2{{E}_{o}}}{c}\hat{j}\,\sin \,kz\,\cos \,\omega t\] done clear
  B)
  \[-\frac{2{{E}_{o}}}{c}\hat{j}\,\sin \,kz\,\sin \,\omega t\] done clear
  C)
  \[\frac{2{{E}_{o}}}{c}\hat{j}\,\sin \,kz\,\sin \,\omega t\] done clear
  D)
  \[\frac{2{{E}_{o}}}{c}\hat{j}\,\cos \,kz\,\cos \,\omega t\] done clear
  View Solution play_arrow

• question_answer31)
  Which of the following has/have zero average value in a plane electromagnetic wave?
  A)
  Both magnetic and electric fields done clear
  B)
  Electric field only done clear
  C)
  Magnetic field only done clear
  D)
  Magnetic energy done clear
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• question_answer32)
  The energy density of electromagnetic wave in vacuum is given by the relation
  A)
  \[\frac{{{E}^{2}}}{2{{\varepsilon }_{0}}}+\frac{{{B}^{2}}}{2{{\mu }_{0}}}\]   done clear
  B)
  \[\frac{1}{2}{{\varepsilon }_{0}}{{E}^{2}}+\frac{1}{2}{{\mu }_{0}}{{B}^{2}}\] done clear
  C)
  \[\frac{{{E}^{2}}+{{B}^{2}}}{c}\] done clear
  D)
  \[\frac{1}{2}{{\varepsilon }_{0}}{{E}^{2}}+\frac{{{B}^{2}}}{2{{\mu }_{0}}}\] done clear
  View Solution play_arrow

• question_answer33)
  The waves which are electromagnetic in nature are
  A)
  sound waves and light waves done clear
  B)
  water waves and radio waves done clear
  C)
  light waves and X-rays done clear
  D)
  sound waves and water waves done clear
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• question_answer34)
  We consider the radiation emitted by the human body. Which of the following statements is true?
  A)
  the radiation emitted lies in the ultraviolet region and hence is not visible. done clear
  B)
  the radiation emitted is in the infra-red region. done clear
  C)
  the radiation is emitted only during the day. done clear
  D)
  the radiation is emitted during the summers and absorbed during the winters. done clear
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• question_answer35)
  An electromagnetic radiation has an energy 11 keV. To which region of electromagnetic spectrum does it belong?
  A)
  X-ray region done clear
  B)
  Ultra violet region done clear
  C)
  Infrared region done clear
  D)
  Visible region done clear
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• question_answer36)
  Electromagnetic radiation of highest frequency is
  A)
  infrared radiations           done clear
  B)
  visible radiation done clear
  C)
  radio waves      done clear
  D)
         \[\gamma -rays\] done clear
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• question_answer37)
  In which one of the following regions of the electromagnetic spectrum will the vibrational motion of molecules give rise to absorption?
  A)
  Ultraviolet       done clear
  B)
         Microwaves done clear
  C)
  Infrared          done clear
  D)
         Radio waves done clear
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• question_answer38)
  Which of the following statements is true?
  A)
  The wavelength of microwaves is greater than that of UV-rays done clear
  B)
  The wavelength of IR rays is lesser than that of UV-rays done clear
  C)
  The wavelength of microwaves is lesser than that of IR rays done clear
  D)
  Gamma rays has largest wavelength in the electromagnetic spectrum. done clear
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• question_answer39)
  Which of the following electromagnetic waves has minimum frequency?
  A)
  Microwaves  done clear
  B)
  Audible waves done clear
  C)
  Ultrasonic wave done clear
  D)
  Radio waves done clear
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• question_answer40)
  All components of the electromagnetic spectrum in vacuum have the same
  A)
  energy done clear
  B)
  velocity done clear
  C)
  wavelength done clear
  D)
  frequency done clear
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• question_answer41)
  The range of wavelength of the visible light is
  A)
  \[10\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,100\overset{o}{\mathop{A}}\,\]               done clear
  B)
  \[4,000\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,\,8,000\overset{o}{\mathop{A}}\,\] done clear
  C)
  \[8,000\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,10,000\overset{o}{\mathop{A}}\,\] done clear
  D)
  \[10,000\,\overset{o}{\mathop{A}}\,\,\,\,to\,\,15,000\overset{o}{\mathop{A}}\,\] done clear
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• question_answer42)
  Given below is a list of electromagnetic spectrum and its mode of production. Which one does not match?
  A)
  Gamma rays - Radioactive decay of the nucleus done clear
  B)
  Ultraviolet rays - Magnetron valve done clear
  C)
  Radio wave - Rapid acceleration and deceleration of electrons in conducting wires done clear
  D)
  X-rays - coolidge tube done clear
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• question_answer43)
  Which of the following shows greenhouse effect?
  A)
  Ultraviolet rays   done clear
  B)
  Infrared rays done clear
  C)
  X-rays done clear
  D)
  None of these done clear
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• question_answer44)
  Given below is a list of E.M spectrum and its use. Which one does not match?
  A)
  U.V. rays - finger prints detection done clear
  B)
  I.R. rays - Secret writing on ancient walls done clear
  C)
  X- rays - Atomic structure done clear
  D)
  Microwaves - forged document detection done clear
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• question_answer45)
  Which radiation in sunlight, causes heating effect?
  A)
  Ultraviolet  done clear
  B)
  Infrared done clear
  C)
  Visible light  done clear
  D)
  All of these done clear
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• question_answer46)
  A capacitor, made of two parallel plates each of plate area A and separation d, is being charged by an external ac source. If \[{{I}_{1}}\] and \[{{I}_{2}}\] be the dis- placement current inside the capacitor and the instantaneous current charging the capacitor, then
  A)
  \[{{I}_{1}}={{I}_{2}}\] done clear
  B)
  \[{{I}_{1}}>{{I}_{2}}\] done clear
  C)
  \[{{I}_{1}}<{{I}_{2}}\] done clear
  D)
  None of these done clear
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• question_answer47)
  An EM wave radiates outwards from a dipole antenna, with \[{{E}_{0}}\] as the amplitude of its electric field vector. The electric field \[{{E}_{0}}\] which transports significant energy from the source falls off as [r = distance from dipole antenna]
  A)
  \[\frac{1}{{{r}^{3}}}\] done clear
  B)
  \[\frac{1}{{{r}^{2}}}\] done clear
  C)
  \[\frac{1}{r}\] done clear
  D)
  remains constant done clear
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• question_answer48)
  Find the average energy density corresponding to maximum electric field, if magnetic field in a plane electromagnetic wave is given by \[B=200\times {{10}^{-6}}\,\sin \,[(4\times {{10}^{15}})(t-x/c)]\]
  A)
  \[1.6\,J\,{{m}^{-3}}\]   done clear
  B)
  \[0.16\,J\,{{m}^{-3}}\]  done clear
  C)
  \[0.016\,J\,{{m}^{-3}}\] done clear
  D)
  \[0.0016\,J\,{{m}^{-3}}\] done clear
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• question_answer49)
  The amplitude of the electric field if the intensity of a plane electromagnetic wave is given as \[2.0\,W{{m}^{-2}}\] is
  A)
  \[38.8\,N{{C}^{-1}}\] done clear
  B)
  \[48.3\,N{{C}^{-1}}\] done clear
  C)
  \[50.2\,N{{C}^{-1}}\] done clear
  D)
  \[68.8\,N{{C}^{-1}}\] done clear
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• question_answer50)
  Which of the following is the correct equation for magnetic field as a function of x, and t where a plane electromagnetic wave propagating in the x-direction has a wavelength of 5.0 mm? The electric field is in the y-direction and its maximum value is \[30\,V{{m}^{-1}}\].        
  A)
  \[B={{10}^{-3}}\,\sin \,\left[ \frac{2\pi }{5\times {{10}^{-3}}}(ct-x) \right]\] done clear
  B)
  \[B={{10}^{-7}}\,\sin \,\left[ \frac{2\pi }{5\times {{10}^{-3}}}(ct-x) \right]\] done clear
  C)
  \[B={{10}^{-5}}\,\sin \,\left[ \frac{\pi }{1.5\times {{10}^{-3}}}(ct-x) \right]\] done clear
  D)
  None of these done clear
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• question_answer51)
  The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is
  A)
  \[c:1\] done clear
  B)
  \[{{c}^{2}}:1\] done clear
  C)
  \[1:1\] done clear
  D)
  \[\sqrt{c}:1\] done clear
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• question_answer52)
  Which of the following waves have the maximum wavelength
  A)
  X-rays done clear
  B)
  I.R. rays done clear
  C)
  UV rays done clear
  D)
  Radio waves done clear
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• question_answer53)
  If microwaves, X rays, infrared, gamma rays, ultra-violet, radio waves and visible parts of the electromagnetic spectrum are denoted by M, X, I, G, U, R and V then which of the following is the arrangement in ascending order of wavelength?
  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
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• question_answer54)
  Microwave oven acts on the principle of:
  A)
  giving rotational energy to water molecules done clear
  B)
  giving translational energy to water molecules done clear
  C)
  giving vibrational energy to water molecules done clear
  D)
  transferring electrons from lower to higher energy levels in water molecule done clear
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• question_answer55)
  Beyond which frequency, the ionosphere bends any incident E.M. radiation but do not reflect it back towards the earth.
  A)
  80 MHz          done clear
  B)
         40 MHz done clear
  C)
  20 MHz          done clear
  D)
         10 MHz done clear
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• question_answer56)
  Radio waves and visible light in vacuum have
  A)
  same velocity but different wavelength done clear
  B)
  continuous emission spectrum done clear
  C)
  band absorption spectrum done clear
  D)
  line emission spectrum done clear
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• question_answer57)
  Which of the following is the infrared ray wavelength?
  A)
  \[{{10}^{-4}}\,cm\]         done clear
  B)
         \[{{10}^{-5}}\,cm\] done clear
  C)
  \[{{10}^{-6}}\,cm\]         done clear
  D)
         \[{{10}^{-7}}\,cm\] done clear
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• question_answer58)
  A parallel plate capacitor with a and separation d, is charged by a constant current I. Consider a plane surface of area\[\frac{a}{2}\]parallel to the plates and drawn symmetrically between the plates. What is the displacement current through this area?
  A)
  \[I/2\] done clear
  B)
  \[I/3\]     done clear
  C)
   \[I/5\] done clear
  D)
  \[I/7\] done clear
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• question_answer59)
  The magnetic field of a beam emerging from a filter facing a floodlight is given by \[{{B}_{0}}=12\times {{10}^{-8}}\,\sin \,(1.20\times {{10}^{7}}z-3.60\times {{10}^{15}}t)T\]. What is the average intensity of the beam?
  A)
  \[1.72\times {{10}^{2}}\,W/{{m}^{2}}\] done clear
  B)
  \[1.72\,W/{{m}^{2}}\] done clear
  C)
  \[2.31\,W/{{m}^{2}}\] done clear
  D)
  \[2.31\,\times {{10}^{2}}W/{{m}^{2}}\] done clear
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• question_answer60)
  The charge on a parallel plate capacitor varies as \[q={{q}_{0}}\,\cos \,2\pi vt\]. The plates are very large and close together (area = A, separation = d). Neglecting the edge effects, the displacement current through the capacitor is
  A)
  \[2\pi v{{q}_{0}}\,\sin \,2\pi vt\] done clear
  B)
  \[3/5\pi v{{q}_{0}}\,\sin \,\pi vt\] done clear
  C)
  \[4\pi v{{q}_{0}}\,\sin \,2\pi vt\] done clear
  D)
  None of these done clear
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• question_answer61)
  The energy contained in a cylinder of cross- section\[10c{{m}^{2}}\]and length 50cm along the x-axis if electric field in an electromagnetic wave is given by \[E=50\,\sin \,\omega (t-x/c)\] is  
  A)
  \[1.2\times {{10}^{-10}}\,J\] done clear
  B)
  \[5.5\times {{10}^{-12}}\,J\] done clear
  C)
  \[2.3\times {{10}^{-10}}\,J\] done clear
  D)
  \[3.6\times {{10}^{-12}}\,J\] done clear
  View Solution play_arrow

• question_answer62)
  Match List-I (Electromagnetic wave type) with List-II (Its association/application) and select the correct option from the choices given below the lists:

  	Column I		Column II
  [a]	Infrared waves	(i)	To treat muscular strain
  [b]	Radio waves	(ii)	For broadcasting
  [c]	X-rays	(iii)	To detect fracture of bones
  [d]	Ultraviolet rays	(iv)	Absorbed by the ozone layer of the atmosphere

  A)
  1-(iv)     2-(iii)     3-(ii)      4-(i) done clear
  B)
  1-(i)                   2-(ii)      3-(iv)     4-(iii) done clear
  C)
  1-(iii)                 2-(ii)      3-(i)       4-(iv) done clear
  D)
  1-(i)                   2-(ii)      3-(iii)     4-(iv) done clear
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• question_answer63)

  Arrange the following electromagnetic radiations per quantum in the order of increasing energy:

  A: Blue light

  B: Yellow light

  C: X-ray

  D: Radio wave.

  A)
  C, A, B, D done clear
  B)
  B, A, D, C done clear
  C)
  D, B, A, C done clear
  D)
  A, B, D, C done clear
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• question_answer64)
  During the propagation of electromagnetic waves in a medium
  A)
  electric energy density is double of the magnetic energy density. done clear
  B)
  electric energy density is half of the magnetic energy density.                                    done clear
  C)
  electric energy density is equal to the magnetic energy density done clear
  D)
  both electric and magnetic energy densities are zero. done clear
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• question_answer65)

  An EM wave of intensity I falls on a surface kept in vacuum and exerts radiation pressure p on it.

  Which of the following is wrong?

  A)
  Radiation pressure is \[\frac{I}{c}\] if the wave is totally absorbed done clear
  B)
  Radiation pressure is \[\frac{I}{c}\] if the wave is totally reflected done clear
  C)
  Radiation pressure is \[\frac{2I}{c}\] if the wave is totally reflected             done clear
  D)
  Radiation pressure is in the range \[\frac{I}{c}<p<\frac{2I}{c}\] for real surfaces done clear
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• question_answer66)
  Which of the following statements is and correct.
  A)
  When variable frequency a.c. Source is connected to a capacitor, displacement current increases with increase in frequency done clear
  B)
  As frequency increases conduction current also increases done clear
  C)
  Short wave bands are used for transmission of radio waves to a large distance done clear
  D)
  Ultraviolet radiation are absorbed by the atmosphere and converts Ozone to Oxygen done clear
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• question_answer67)

  A charged particle oscillates about its mean equilibrium position with a frequency of \[{{10}^{9}}\text{ }Hz\].

  The electromagnetic waves produced

  A)
  will have frequency of \[{{10}^{6}}\text{ }Hz\] done clear
  B)
  will have frequency of \[2\times {{10}^{3}}\ Hz\] done clear
  C)
  will have wavelength of 0.3 m done clear
  D)
  fall in the region of U.V. waves done clear
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• question_answer68)
  The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is
  A)
  \[3V/m\] done clear
  B)
  \[6V/m\] done clear
  C)
  \[9V/m\] done clear
  D)
  \[12V/m\] done clear
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• question_answer69)
  In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of \[2.0\text{ }\times \text{ }{{10}^{10}}\] Hz and amplitude \[48\,V\,{{m}^{-1}}\]. Then
  A)
  the wavelength of the wave is \[1.5\times {{10}^{-5}}\text{ }m\] done clear
  B)
  the amplitude of the oscillating magnetic field is \[16\times {{10}^{-3}}T\] done clear
  C)
  the average energy density of the E is equal to the average energy density of the B. \[[c=3\times {{10}^{8}}\,m\,{{s}^{-1}}.]\] done clear
  D)
  None of these done clear
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• question_answer70)
  An LC resonant circuit contains a 4 pF capacitor and a 10 mH inductor. It is set into oscillation coupled to an instrument. The wavelength of the radiated electromagnetic waves is:
  A)
  355 cm    done clear
  B)
  377 m done clear
  C)
  400 mm  done clear
  D)
  600 mm done clear
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