JEE Main & Advanced Physics EM Waves Question Bank

done Mock Test - Electromagnetic Waves and Dual Nature Total Questions - 25

• question_answer1)
  A parallel plate capacitor with plate area A and separation between the plates J, is charged by a constant current i. Consider a plane surface of area all parallel to the plates and drawn simultaneously between the plates. The displacement current through this area is
  A)
  \[i\]                   done clear
  B)
  \[i/2\] done clear
  C)
  \[i/4\]                 done clear
  D)
  \[i/8\]   done clear
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• question_answer2)
  In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of \[2.5\times {{10}^{10}}Hz\] and amplitude 480 V/m. The amplitude of the oscillating magnetic field will be
  A)
  \[1.52\times {{10}^{-8}}Wb/{{m}^{2}}\]         done clear
  B)
  \[1.52\times {{10}^{-7}}Wb/{{m}^{2}}\] done clear
  C)
  \[1.6\times {{10}^{-6}}Wb/{{m}^{2}}\] done clear
  D)
  \[1.6\times {{10}^{-7}}Wb/{{m}^{2}}\] done clear
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• question_answer3)
  A plane electromagnetic wave \[{{E}_{z}}=100\cos (6\times {{10}^{8}}t+4x)V/m\] propagates in a medium of dielectric constant
  A)
  1.5 done clear
  B)
   2.0 done clear
  C)
  2.4                    done clear
  D)
  4.0 done clear
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• question_answer4)
  Light from a hydrogen discharge tube is incident on the cathode of a photoelectric cell. The work function of the cathode surface is 4.2 eV. In order to reduce the photo- current to zero the voltage of the anode relative to the cathode must be made
  A)
  -4.2V    done clear
  B)
  -9.4V done clear
  C)
  -17.8V   done clear
  D)
  +9.4 V done clear
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• question_answer5)
  The potential energy of a particle of mass m is given by \[U(x)=\left\{ \begin{matrix}    {{E}_{0}};  \\    0;  \\ \end{matrix}\begin{matrix}    0\le x\le 1  \\    x>1  \\ \end{matrix} \right.\] \[{{\lambda }_{1}}\] and \[{{\lambda }_{2}}\] are the de Broglie wavelengths of the particle, when \[0\le x\le 1\]and \[x>1\] respectively. If the total energy of particle is 2\[{{E}_{0}}\], the ratio \[\frac{{{\lambda }_{0}}}{{{\lambda }_{2}}}\] will be
  A)
  2                      done clear
  B)
  1          done clear
  C)
  \[\sqrt{2}\]         done clear
  D)
  \[\frac{1}{\sqrt{2}}\] done clear
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• question_answer6)
  The ratio of de Broglie wavelength of a a-particle to that of a proton being subjected to the same magnetic field so that the radii of their paths are equal to each other assuming the field induction vector \[\vec{B}\] is perpendicular to the velocity vectors of the a-particle and the proton is
  A)
  1                      done clear
  B)
  \[\frac{1}{4}\] done clear
  C)
  \[\frac{1}{2}\]   done clear
  D)
  \[2\] done clear
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• question_answer7)
  According to Einstein's photoelectric equation, the plot of the kinetic energy of the emitted photoelectrons from a metal versus the frequency of the incident radiation gives a straight line whose slope
  A)
  Depends on the nature of the metal used done clear
  B)
  Depends on the intensity of the radiation done clear
  C)
  Depends both on the intensity of the radiation and the metal used done clear
  D)
  Is the same for all metals and independent of the intensity of the radiation? done clear
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• question_answer8)
  How many photons of a radiation of wavelength \[\lambda =5\times {{10}^{-7}}m\] must fall per second on a blackened plate in order to produce a force of \[6.62\times {{10}^{-5}}\]N?
  A)
  \[3\times {{10}^{19}}\] done clear
  B)
  \[5\times {{10}^{22}}\] done clear
  C)
  \[2\times {{10}^{22}}\] done clear
  D)
  \[1.67\times {{10}^{18}}\] done clear
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• question_answer9)
  The rms value of the electric field of the light coming from sun is 720 N/C. The average energy density of the emf is
  A)
  \[3.3\times {{10}^{-3}}J/{{m}^{3}}\] done clear
  B)
  \[4.58\times {{10}^{-6}}J/{{m}^{3}}\] done clear
  C)
  \[6.37\times {{10}^{-9}}J/{{m}^{3}}\]            done clear
  D)
  \[81.35\times {{10}^{-12}}J/{{m}^{3}}\] done clear
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• question_answer10)
  An electron is accelerated through a potential difference of V volt. It has a wavelength \[\lambda \] associated with it. Through what potential difference an electron must be accelerated so that its de Broglie wavelength is the same as that of a Proton? Take mass of proton to be 1837 times larger than the mass of electron.
  A)
  \[Vvolt\] done clear
  B)
  \[1837V\,volt\] done clear
  C)
  \[V/1837\,volt\]   done clear
  D)
  \[\sqrt{1837}V\,volt\] done clear
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• question_answer11)
  What is the de Broglie wavelength of the wave associated with an electron that has been accelerated through a potential difference of 50.0 V?
  A)
  \[2.7\times {{10}^{-10}}\]         done clear
  B)
  \[1.74\times {{10}^{-10}}\] done clear
  C)
  \[3.6\times {{10}^{-9}}\]          done clear
  D)
  \[4.9\times {{10}^{-11}}\] done clear
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• question_answer12)
  Two electrons are moving with same speed v. One electron enters a region of uniform electric field while the other enters a region of uniform magnetic field, then after some time de Broglie wavelengths of two are \[{{\lambda }_{1}}\] and\[{{\lambda }_{2}}\], respectively. Now,
  A)
  \[{{\lambda }_{1}}={{\lambda }_{2}}\] done clear
  B)
  \[{{\lambda }_{1}}>{{\lambda }_{2}}\] done clear
  C)
  \[{{\lambda }_{1}}<{{\lambda }_{2}}\] done clear
  D)
  \[{{\lambda }_{1}}\]can be greater than or less than \[{{\lambda }_{2}}\] done clear
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• question_answer13)
  Which of the following is not a possible de-Broglie's wavelength of a particle, which moves inside a cubical box of side length L, without losing any energy (elastically colliding with walls of cube)?
  A)
        done clear
  B)
  done clear
  C)
    done clear
  D)
  All of these done clear
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• question_answer14)
  A material particle with a rest mass \[{{m}_{0}}\] is moving with a velocity of light c. Then, the wavelength of the de Broglie wave associated with it is
  A)
  \[(h/{{m}_{0}}c)\]         done clear
  B)
  Zero done clear
  C)
  \[\infty \]                        done clear
  D)
  \[({{m}_{0}}c/h)\] done clear
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• question_answer15)
  If the intensity of radiation incident on a photocell be increased four times, then the number of photoelectrons and the energy of photoelectrons emitted respectively become
  A)
  Four times, doubled done clear
  B)
  Doubled, remains unchanged done clear
  C)
  Remains unchanged, doubled done clear
  D)
  Four times, remains unchanged done clear
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• question_answer16)
  Given that a photon of light of wavelength 10,000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] has an energy equal to 1.23 eV. When light of wavelength 5000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] and intensity \[{{I}_{0}}\] falls on a photoelectric cell, the saturation current is \[0.40\times {{10}^{-6}}\]\[\overset{\text{o}}{\mathop{\text{A}}}\,\] and the stopping potential is 1.36 V; then the work function is
  A)
  \[0.43\,eV\]        done clear
  B)
  \[1.10\,eV\] done clear
  C)
  \[1.36\,eV\]        done clear
  D)
  \[2.47\,eV\] done clear
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• question_answer17)
  A plane em wave of wave intensity of \[10\,W/{{m}^{2}}\] strikes a small mirror of area 20\[c{{m}^{2}}\], held perpendicular to the approaching wave. The radiation force on the mirror will be
  A)
  \[6.6\times {{10}^{-11}}N\]      done clear
  B)
  \[1.33\times {{10}^{-11}}N\] done clear
  C)
  \[1.33\times {{10}^{-10}}N\] done clear
  D)
  \[6.6\times {{10}^{-10}}N\] done clear
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• question_answer18)
  The work function of a metallic surface is 5.01 eV. The photoelectrons are emitted when light of wavelength 2000 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] falls on it. The potential difference applied to stop! The fastest photoelectrons is \[\left[ h=4.14\times {{10}^{-15}}eVs \right]\]
  A)
  1.2 V    done clear
  B)
  2.24 V done clear
  C)
  3.6 V    done clear
  D)
  4.8 V done clear
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• question_answer19)
  In the experiment on photoelectric effect, the graph between \[{{E}_{K}}_{(max)}\] is found to be a straight line as shown in figure. The threshold frequency and Planck's constant according to this graph are
  A)
  \[3.33\times {{10}^{18}}{{s}^{-1}},\,\,6\times {{10}^{-34}}J\text{-}s\] done clear
  B)
  \[6\times {{10}^{18}}{{s}^{-1}},6\times {{10}^{-34}}J\text{-}s\] done clear
  C)
  \[2.66\times {{10}^{18}}{{s}^{-1}},\,\,4\times {{10}^{-34}}J\text{-}s\] done clear
  D)
  \[4\times {{10}^{18}}{{s}^{-1}},\,\,3\times {{10}^{-34}}J\text{-}s\]   done clear
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• question_answer20)
  The transmitting antenna of a radio-station is mounted vertically. At a point 10 km due north of the transmitter the peak electric field is\[{{10}^{-3}}\,V\text{/}m.\] The amplitude of the radiated magnetic field is
  A)
  \[3.33\times {{10}^{-10}}T\]     done clear
  B)
  \[3.33\times {{10}^{-12}}T\] done clear
  C)
  \[{{10}^{-13}}T\]        done clear
  D)
  \[3\times {{10}^{5}}T\] done clear
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• question_answer21)
  Radio receiver antenna that is 2 m long is oriented along the direction of the electromagnetic wave and receives a signal of intensity\[5\times {{10}^{-16}}W/{{m}^{2}}\]. What is the maximum Instantaneous potential difference (in\[\mu V\]) across the two ends of the antenna?
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• question_answer22)
  A plane electromagnetic wave propagating in the x-direction has wavelength of 60 mm. The electric field is in the y-direction and its maximum magnitude is\[33\,V/{{m}^{-1}}\]. The equation for the electric field as function of x and t is N\[\sin \pi \times {{10}^{11}}(t-x/c)\]. Find the value of N.
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• question_answer23)
  A circular ring of radius r is placed in a homogeneous! magnetic field perpendicular to the plane of the ring. TN field B changes with time according to the equation\[B=Kt\], where K is a constant and t is the time. The electric field in the ring is\[\frac{Kr}{P}\] Find the value of P.
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• question_answer24)
  If 10000 V is applied across an X-ray tube, what will be the ratio of de Broglie wavelength of the incident electron to the shortest wavelength of X-ray produced?  \[(\frac{e}{m}\text{for}\,\text{electron}\,\,\text{is}\,1.8\times {{10}^{11}}Ck{{g}^{-1}})\]
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• question_answer25)
  Silver has a work function of 4.7 eV. When ultraviolet light of wavelength 100 mm is incident upon it, a potential of 7.7 V is required to stop the photoelectrons from reaching the collector plate. How much potential (in V) will be required to stop the photoelectrons when light of wavelength 200 mm is incident upon silver?
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