Q.1
Photoelectrons of energy 2eV are emitted from a metal surface when photons of energy 5eV are incident on it. What will be the energy of emitted photoelectrons when photons of energy 6eV are incident on it
  • a) 3eV
  • b) 4eV
  • c)2eV
  • d)5eV
Q.2
In majority of crystals the value of lattice constant is of order of 3 Å. The proper X-rays with which the crystal structure can be studied are
  • a)50Å to 100Å
  • b) 10Å to 50Å
  • c)5Å to 10Å
  • d)0.1Å to 2.7Å
Q.3
The distance between two success atomic planes of calcite crystal is 0.3Å. the minimum angle for Bragg scattering of 0.3Å X-ray will be
  • a) 1.5°
  • b) 30°
  • c)2.86°
  • d)60°
Q.4
The velocity of electron emitted in photoelectric effect depends on the properties of photosensitive surface an
  • a) frequency of incident light
  • b) state of polarization of incident light
  • c)time for which light is incident
  • d) intensity of incident light
Q.5
De-Broglie wavelength of a particle moving with velocity 2.25×108 m/s is same at the wave length of photon. The ratio of kinetic energy of the particle to the energy of photon is
  • a) 1/8
  • b) 3/8
  • c) 5/8
  • d) 7/8
Q.6
Energy of photon is E=hν and its momentum is p=h/λ, where λ is the wavelength of photon, with this assumption, speed of light wave is
  • a)3×108 m/s
  • b) E/p
  • c)Ep
  • d)(E/p)2
Q.7
Monochromatic light is incident on a phtocell from a source lying at the distance of 0.2 m. The stopping potential and the saturated current are 0.6V and 18.0 mA respectively. Now on displacing the source at the distance 0.6m from the photocell...
  • a) stopping potential will be 0.2V
  • b) stopping potential will be 0.9V
  • c)saturated current will be 6mA
  • d)Saturated current will be 2mA
Q.8
A proton and alpha particle are passed through same potential difference. If their initial velocity is zero, the ratio of their de-broglie wavelength after getting accelerated is .. [ GUJCET 2007]
  • a) 1:1
  • b) 1:2
  • c)2:1
  • d)2√2 :1
Q.9
Mass of photon in motion is ..[GUJCET 2008]
  • a) c/hν
  • b) h/λ
  • c) hν
  • d) hν/c²
Q.10
Wavelength of an electron having energy 10keV is ..Å
  • a)0.12
  • b) 1.2
  • c)12
  • d)120
Q.11
If the momentum of an electron is required to be same as that of wave of 5200Å wave length, its velocity should be [GUJCET 2008]
  • a) 103 m/s
  • b) 1.2 ×103
  • c)1.4 × 103
  • d)2.8 × 103
Q.12
If the uncertainty in position of a particle is same as it's de-Broglie wavelength, then the uncertainty in its momentum is
  • a) h/(2πλ)
  • b) h/(3πλ)
  • c) 2πh/(λ)
  • d)3λ/π
Q.13
A proton and electron are lying in a box having un-penetrable walls, the ratio of uncertainty in their velocities are ...., me is mass of electron, mp is mass of proton
  • a) me/mp
  • b) me × mp
  • c) √(me × mp)
  • d) √(me/me × mp)
Q.14
Which of the following energies are not possible for a microscopic oscillator having frequency f?
  • a) 1.6 hf
  • b) 3.5 hf
  • c)4.8 hf
  • d)all of them
Q.15
If photoelectric effect is not seen with X-ray in a given metal, photoelectron may be emitted by
  • a) infra-red rays
  • b) γ rays
  • c) visible
  • d) ultra violet rays
Q.16
The dimensional formula of Plank's constant is
  • a)M1L1T-2
  • b)M1L2T-3
  • c)M1L2T-2
  • d)M1L2T-1
Q.17
An image of sun is formed by a lens of focal length 30 cm on the metal surface of a photoelectric cell and it produces current I. The lens forming the image is replaced by another lens of the same diameter but focal length 15 cm. the photoeletric current in this case will be ..
  • a)I/2
  • b) I
  • c)2I
  • d)4I
Q.18
When U.V. light is incident on a photocell its work function is φ and maximum kinetic energy of the photoelectrons is Kmax. When X-ray are incident on the same cell...
  • a) Both φ and Kmax increase
  • b) both decrease
  • c)Kmax increases , φ remains same
  • d)Kmax remains same, φ increases
Q.19
The threshold frequency of a photo-sensitive metal is fo. When it is illuminated by light of frequency 2fo the stopping potential is Vo and maximum velocity of electron is vo. What will be the stopping potential when the same metal is illuminated by light of frequency 3fo
  • a) Vo
  • b) 2Vo
  • c)3Vo
  • d)4Vo
Q.20
In situation of Q255, what will be the maximum velocity of the photoelectrons?
  • a) √2 Vo
  • b) 2 Vo
  • c) 2√2 Vo
  • d) 4Vo
Q.21
Violet light can cause photoelectric emission from a metal but blue cannot. If sodium light is incident on the metal, then ....
  • a)photoelectric current decreases
  • b) photoelectric current increases
  • c)photoelectric current is zero
  • d)photoelectric current remains same
Q.22
The maximum kinetic energy of photoelectrons emitted from a metal surface is doubled when the wavelength of the incident radiation is reduced from λ1 to λ2, then the work function of the metal is .....
  • a)
    ch-9_qn-258choice_img_no1.png
  • b)
    ch-9_qn-258choice_img_no2.png
  • c)
    ch-9_qn-258choice_img_no3.png
  • d)
    ch-9_qn-258choice_img_no4.png
Q.23
1020 photons of wavelength 660nm are emitted from a lamp per second. What is the wattage of the lamp
  • a) 30 W
  • b) 60 W
  • c)100 W
  • d)120 W
Q.24
When a certain metallic surface is illuminated with light of wavelength λ, the stopping potential of the photoelectrons is 3Vo. when the same surface is illuminated by light of wavelength 2λ, the stopping potential is Vo. Then threshold wavelength of the metal is ..
  • a) 2λ
  • b) 4λ
  • c) 6λ
  • d) 8λ
Q.25
A proton is moving with velocity v in a region containing uniform electric field E and magnetic field B. All are mutually perpendicular. the proton will move un-deflected if
  • a)v ≥ E/B
  • b) V < E/B
  • c)v=E/B
  • d)v=B/E
Q.26
When green light is incident on a certain metal surface, electrons are emitted, but no electrons are emitted by yellow light. If now red light is made incident on the same metal, then
  • a) more energic electrons are emitted
  • b) less enerrgic electrons are emitted
  • c)no electrons are emitted
  • d)emission of electrons will depend on the intensity of light
Q.27
The work function of a substance is 4eV. the longest wavelength of light that can cause photoelectric emission from the substance is approximately [ GUJCET 2006]
  • a) 400 nm
  • b) 310 nm
  • c)220 nm
  • d)540 nm
Q.28
λo is the de-Broglie wavelength for proton accelerated through a potential difference of 110V, the de-Broglie wavelength for α-particles accelerated through the same potential difference is ...[ GUJCET 2006]
  • a) λo /2
  • b) λo / 2√2
  • c) λo / √2
  • d) (2√2 )λo
Q.29
Monochromatic light of frequency f1 is incident on a photocell and the stopping potential is found to be VWhat is the new stopping potential of the cell it is irradiated by monochromatic light of frequency f2 [ GUJCET 2006]
  • a)
    ch-9_qn-265choice_img_no1.png
  • b)
    ch-9_qn-265choice_img_no2.png
  • c)
    ch-9_qn-265choice_img_no3.png
  • d)
    ch-9_qn-265choice_img_no4.png
Q.30
The threshold wavelength for a metal having workfunction Wo is λo. What is the threshold wavelength for a metal whose workfunction is Wo /2? [ GUJCET 2007]
  • a) 4λo
  • b) 2λo
  • c)λo/2
  • d)λo /4
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