Dual Nature of Matter & Radiation PYQs Set 3 (PDF)

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Mere Teacher · Previous Year Questions NEET Physics · Dual Nature of Matter & Radiation · Set 3 (Q61-90)
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61. $Two sources of light emit with a power of 200 W . The ratio of number of photons of visible light emitted by each source having wavelengths 300 nm and 500 nm respectively, will be:$ (1) $1 : 5$ (2) $1 : 3$ (3) $5 : 3$ (4) $3 : 5$ 62. $When the light of frequency 2 v_{0} (where, v_{0} is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v_{1} . When the frequency of the incident radiation is increased to 5 v_{0}, the maximum velocity of electrons emitted from the same plate is v_{2} . The ratio of v_{1} to v_{2} is [NEET 2018]$ (1) $4 : 1$ (2) $1 : 4$ (3) $1 : 2$ (4) $2 : 1$ 63. $A metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V_{0} . If the same surface is illuminated with radiation of wavelength 2 λ, the stopping potential becomes \frac{V _{0}}{4} . The threshold wavelength for this metallic surface will be$ (1) $3 λ$ (2) $4 λ$ (3) $\frac{3}{2} λ$ (4) $\frac{λ}{4}$ 64. $The ratio of the de-Broglie wavelengths of proton and electron having same kinetic energy: (Assume m_{p} = m_{e} x 1849)$ (1) $1 : 43$ (2) $1 : 30$ (3) $1 : 62$ (4) $2 : 43$ 65. $In photoelectric effect, stopping potential for a light of frequency n_{1} is V_{1} . If light is replaced by another having a frequency n_{2}, then its stopping potential will be$ (1) $V_{1} - \frac{h}{e} (n_{2} - n_{1})$ (2) $V_{1} + \frac{h}{e} (n_{2} + n_{1})$ (3) $V_{1} + \frac{h}{e} (n_{2} - 2 n_{1})$ (4) $V_{1} + \frac{h}{e} (n_{2} - n_{1})$ 66. $An α particle and a proton are accelerated from rest through the same potential difference. The ratio of linear momenta acquired by above two particals will be:$ (1) $2 : 1$ (2) $2 2 : 1$ (3) $4 2 : 1$ (4) $8 : l$ 67. $The de-Broglie wavelength associated with an electron, accelerated through a potential difference of 121 volts is about: [Take Plank's constant = h = 6.6 \times 10^{- 34} J.s, mass of electron (9 \times 10^{- 31} kg)$ (1) $0.123 nm$ (2) $0.112 nm$ (3) $0.221 nm$ (4) $0.098 nm$ 68. $The metal which has the highest work function in the following is$ (1) $Cesium (Cs)$ (2) $Sodium (Na)$ (3) $Aluminium (Al)$ (4) $Platinum (Pt)$ 69. $The ratio of de-Broglie wavelength of an α -particle and a proton accelerated from rest by the same potential is \frac{1}{m}, the value of m is$ (1) $4$ (2) $16$ (3) $8$ (4) $2$ 70. $Find the de-Broglie wavelength of an electron with kinetic energy of 120 eV .$ (1) $102 pm$ (2) $124 pm$ (3) $95 pm$ (4) $112 pm$ 71. $Electron beam used in an electron microscope, when accelerated by a voltage of 20 kV. has a de-Broglie wavelength of λ_{0} . If the voltage is increased to 40 kV. then the de-Broglie wavelength associated with the electron beam would be:$ (1) $3 λ_{0}$ (2) $9 λ_{0}$ (3) $\frac{λ _{0}}{2}$ (4) $\frac{λ _{0}}{2}$ 72. $A proton and an alpha particle are accelerated under the same potential difference. The ratio of de-Broglie wavelengths of the proton and the alpha particle is$ (1) $8$ (2) $\frac{1}{8}$ (3) $1$ (4) $2$ 73. $A and B are two metals with threshold frequencies 1.8 \times 1 0^{14} H z and 2.2 \times 1 0^{14} H z . Two identical photons of energy 0.825 e V each are incident on them. Then photoelectrons are emitted in (Take h = 6.6 \times 1 0^{- 34} J s)$ (1) $B alone$ (2) $A alone$ (3) $neither A nor B$ (4) $both A and B .$ 74. $' n' photons of wavelength ' λ' are absorbed by a black body of mass ' m'. The momentum gained by the body is$ (1) $\frac{h}{mλ}$ (2) $\frac{mnh}{λ}$ (3) $\frac{nh}{mλ}$ (4) $\frac{nh}{λ}$ 75. $The correct match between the entries in column I and column II are Column I Radiation (A) Microwave (B) Gamma rays (C) A.M. radio waves (D) X = rays Column II Wavelength (I) 100 m (II) 10^{- 15} m (III) 10^{- 10} m (IV) 10^{- 3} m$ (1) $(A) - (II), (B) - (I), (C) - (IV), (D) - (III)$ (2) $(A) - (I), (B) - (III), (C) - (IV), (D) - (II)$ (3) $(A) - (III), (B) - (II), (C) - (I), (D) - (IV)$ (4) $(A) - (IV), (B) - (II), (C) - (I), (D) - (III)$ 76. $If λ and K are de Broglie wavelength and kinetic energy, respectively, of a particle with constant mass. The correct graphical representation for the particle will be$ (1) (2) (3) (4) 77. $The de Broglie wavelength of a proton ( charge = 1.6 \times 10^{- 19} C, mass = 1.6 \times 10^{- 27} kg) accelerated through a potential difference of 1 kV is$ (1) $600Å$ (2) $0.9 \times 10^{- 12} m$ (3) $7Å$ (4) $0.9Å$ 78. $A proton of mass ' m_{p}' has same energy as that of a photon of wavelength ' λ'. If the proton is moving at nonrelativistic speed, then ratio of its de Broglie wavelength to the wavelength of photon is.$ (1) $\frac{1}{c} \frac{E}{m _{p}}$ (2) $\frac{1}{c} \frac{2 E}{m _{p}}$ (3) $\frac{1}{2 c} \frac{E}{m _{p}}$ (4) $\frac{1}{c} \frac{E}{2 m _{p}}$ 79. $Electrons used in an electron microscope are accelerated by a voltage of 25 kV If the voltage is increased to 100 kV then the de‐Broglie wavelength associated with the electrons would$ (1) $increase by 2 times$ (2) $decrease by 2 times$ (3) $decrease by 4 times$ (4) $increase by 4 times$ 80. $The voltage applied to an electron microscope to produce electrons of wavelength 0.50Å is$ (1) $602 V$ (2) $50 V$ (3) $138 V$ (4) $812 V$ 81. $A certain metallic surface is illuminated with monochromatic light of wavelength, λ . The stopping potential for photoelectric current for this light is 3 V_{0} . If the same surface is illuminated with light of wavelength 2 λ, the stopping potential is V_{0} . The threshold wavelength for this surface for photo‐electric effect is$ (1) $\frac{λ}{4}$ (2) $\frac{λ}{6}$ (3) $6 λ$ (4) $4 λ .$ 82. $The de-Broglie wavelength of an electron moving with kinetic energy of 144 eV is nearly [NEET 2020]$ (1) $102 \times 10^{- 3} nm$ (2) $102 \times 10^{- 4} nm$ (3) $102 \times 10^{- 5} nm$ (4) $102 \times 10^{- 2} nm$ 83. $Who evaluated the mass of electron indirectly with help of charge$ (1) $Thomson$ (2) $Millikan$ (3) $Rutherford$ (4) $Newton$ 84. $A beam of photons with an energy of 10.5 eV strike a metal plate. The photoclectrons are emitted with maximum velocity of 1.6 \times 10^{6} \frac{m}{s} . The work-function of the metal is (assume, mass of electron = 9 \times 10^{- 31} kg and charge of electron = 1.6 \times 10^{- 19} C$ (1) $3.0 eV$ (2) $3.1 eV$ (3) $3.3 eV$ (4) $3.5 eV$ 85. $When monochromatic light of wavelength ' λ' is incident on a metallic surface, the stopping potential for photoelectric current is ' 3 V_{0}'. When same surface is illuminated with light of wavelength ' 2 λ', the stopping potential is ' V_{0}'. The threshold wavelength for this surface when photoelectric effect takes place is$ (1) $λ$ (2) $2 λ$ (3) $3 λ$ (4) $4 λ$ 86. $A certain metallic surface is illuminated with monochromatic light of wavelength λ. The stopping potential for photoelectric current for this light is 3 V_{0} . If the same surface is illuminated with light of wavelength 2λ, the stopping potential is V_{0} . The threshold wavelength for this surface for photoelectric effect is$ (1) $6λ$ (2) $4λ$ (3) $λ /4$ (4) $λ /6$ 87. $The number of photons falling per second on a completely darkened plate to produce a force of 6.62 \times 10^{- 5} N is n . If the wavelength of the light falling is 5 \times 10^{- 7} m, then n \times 10^{22} . (h = 6.62 \times 10^{- 34} J s)$ (1) $1$ (2) $5$ (3) $0.2$ (4) $3.3$ 88. $A photon of energy 4 eV imparts all its energy to an electron that leaves a metal surface with 1.1 eV of kinetic energy. The work function of the metal is$ (1) $2.9 . eV$ (2) $5.1 eV$ (3) $3.64 eV$ (4) $4.4 eV$ 89. $The threshold frequency for a photosensitive metal is 3.3 \times 1 0^{14} Hz. If light of frequency 8.2 \times 1 0^{14} Hz is incident on this metal, the cut‐off voltage for the photoelectron emission is nearly$ (1) $1 V$ (2) $2 V$ (3) $3 V$ (4) $5 V$ 90. $Choose the correct option relating wavelengths of different parts of electromagnetic wave spectrum$ (1) $λ_{x - rays} < λ_{microwaves} < λ_{radio waves} < λ_{visible}$ (2) $λ_{visible} > λ_{x rays} > λ_{radio waves} > λ_{micro waves}$ (3) $λ_{radio waves} > λ_{micro waves} > λ_{visible} > λ_{x - rays}$ (4) $λ_{visible} < λ_{micro waves} < λ_{radio waves} < λ_{x - rays}$