Q.1
A photo-cell employ photoelectric effect to convert [ CBSE-PMT 2006]
  • a) Change in the intensity of illumination into a change in photoelectric current
  • b) Change in the intensity of illumination into a change in the work function of the photocathode
  • c)change in the frequency of light into a change in the electric current
  • d)change in the frequency of light into a change in electric voltage
Q.2
The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200nm falls on it, must be..[ CBSE-PMT 2010]
  • a) 2.4V
  • b) -1.2V
  • c)-2.4V
  • d)1.2V
Q.3
The threshold frequency for photoelectric effect on sodium corresponds to a wavelength of 5000 Å its work function is [ CBSE-PMT 1988]
  • b) 1 J
  • a)4 ×10⁻¹⁹ J
  • c)2× 10⁻¹⁹ J
  • d)3 ×10⁻¹⁹ J
Q.4
Electrons used in an electron microscope are accelerated by a voltage of 25kV. If the voltage is increased by 100kV then the de-Broglie wavelength associated with electrons would.. [ CBSE-PMT 2011]
  • a) increase by 2 times
  • b) decrease by 2 times
  • c)decrease by 4 times
  • d)increase by 4 times
Q.5
Monochromatic light of wave length 667 nm is produced by a helium neon laser. The power emitted is 9mW. The number of photons arriving per second on the average at a target irradiated by this beam is [ CBSE-PMT 2009]
  • a) 3×1016
  • b) 9×1015
  • c) 3×1019
  • d) 9×1017
Q.6
In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of [ CBSE-PMT 2008]
  • a)excitation of electons in the atoms
  • b) Collision between the atoms of the gas
  • c)Collision between the charges particles emitted from the cathode and the atoms of the gas
  • d)Collision between different electrons of atoms of the gas
Q.7
In discharge tube ionization of enclosed gas is produced due to collisions between [ CBSE-PMT 2006]
  • a) negative electrons and neutral atoms / molecules
  • b) photons and neutral atoms/ molecule
  • c)neutral gas atoms / molecules
  • d)positive ions and neutral atoms/molecule
Q.8
Photoelectric emission occurs only when the incident light has more than a certain minimum [ CBSE-PMT 2011]
  • a) power
  • b) wavelength
  • c)intensity
  • d)frequency
Q.9
When ultraviolet radiation is incident on a surface, no photoelectrons are emitted. If a second beam causes photoelectrons to be ejected, it may consist of [ CBSE-PMT 2002]
  • a) infra-red waves
  • b) X-rays
  • c) Visible light rays
  • d) radio waves
Q.10
A source S1 is producing, 1015photons per second of wavelength 5000Å . Another source S2 is producing 1.02×1015 photon per second of wave length 5100Å, then ratio of power of Source S2 and power of Source S1 [ CBSE-PMT 2010]
  • a)1.00
  • b) 1.02
  • c)1.04
  • d)0.98
Q.11
A photoelectric cell is illuminated by a point source of light 1m away. When the source is shifted to 2m then [ CBSE-PMT 2003]
  • a) number of electrons emitted is a quarter of initial number
  • b) each emitted electron carries one quarter of the initial energy
  • c)number of electrons emitted is half the initial number
  • d)each emitted electron carries half the initial energy
Q.12
When light of wave length 300 nm falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, however, light of 600nm wavelength is sufficient for creating photoemission. What is the ratio of the work functions of the two emitters? [ CBSE-PMT 1993]
  • a) 1:2
  • b) 2:1
  • c)4:1
  • d)1:4
Q.13
A radio transmitter operates at a frequency 880kHz and a power of 10kW. the number of photons emitted per second is .. [ CBSE-PMT 1990]
  • a) 1.72×1031
  • b) 1.327×1025
  • c) 1.327×1037
  • d) 1.327×1045
Q.14
An electron of mass m and charged e is accelerated from rest through a potential difference of V volt in vacuum. Its final speed will be.. [ CBSE-PMT 1996]
  • a)
    ch-9_qn-46choice_img_no1.png
  • b)
    ch-9_qn-46choice_img_no2.png
  • c)
    ch-9_qn-46choice_img_no3.png
  • d)
    ch-9_qn-46choice_img_no4.png
Q.15
The de-Broglie wavelength associated with a proton changes by 0.25% if its momentum is changed by Po. The initial momentum of proton is
  • a)100Po
  • b) 400Po
  • c)Po/400
  • d)Po
Q.16
Work function for metals A, B, and C are respectively 1.92eV, 2.0eV and 5eV According to Einstein's equation, the metals which will emit photoelectrons for a radiation of wavelength 4100Å
  • a)none
  • b) A only
  • c)A and B only
  • d)All three metals
Q.17
A 5 watt source emits monochromatic light of wavelength 5000Å. When placed 0.5m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0m, the number of photoelectrons liberated will be reduced by a factor of [ CBSE-PMT 2007]
  • a) 8
  • b) 16
  • c) 2
  • d) 4
Q.18
The threshold frequency for a photosensetive metal is 3.3×1014 Hz. If light of frequency 8.2×1014 Hz is incident on this metal, the cut-off voltage for the photoelectric emission is nearly [ CBSE-PMT 2011]
  • a)2V
  • b) 3V
  • c)5V
  • d)1V
Q.19
The cathode of photoelectric cell is changed such that the work function changes from W1 to w2 ( W1 > w2). If the current before and after changes are I1 and Iall other conditions remain unchanged, then ( assuming hν > W2) [ CBSE-PMT 1992]
  • b) I1 < I2
  • c)I1 > I2
  • d)I1< I2<2I1
  • a) I₁=I₂
Q.20
In photo-emissive cell, with exciting wave length λ, the fastest electron speed 'v' . If the exciting wavelength is changed to 3λ / 4 , the speed of the fastest emitted electron will be [ CBSE-PMT 1998]
  • a) (3/4) 1/2 v
  • b) (4/3) 1/2 v
  • c) less than (4/3) 1/2 v
  • d) grater than (3/4) 1/2 v
Q.21
When photoelectric emission is taking place increasing the intensity of light will [ EAMCET 1995, MPPMT 1994]
  • a)have no effect
  • b) increase the number of electrons released
  • c)increases the maximum energy per electron
  • d)causes a time delay in the emission of electrons
Q.22
A photo cell is illuminated by a small bright source of light is placed two metres away, the electrons emitted by the photocathode ..[ MNR 1986]
  • a) each carries one quarter of its previous energy
  • b) each carries one quarter of its previous momentum
  • c)are half as numerous
  • d)are one quarter as numerous
Q.23
Photoelectric effect is the phenomenon in which ..[ MNR1992]
  • a) Photons come out of metal when it is heat by a beam of electrons
  • b) Photons come out of the nucleus of an atom under the action of an electric field
  • c) Electrons come out of a metal with a constant velocity which depends up on the frequency and intensity of incident light wave
  • d) Electrons come out of metal with different velocities not greater than a certain value which depends only on the frequency of incident light wave and not on its intensity
Q.24
What is the stopping potential, when the metal with work function 0.6 eV is illuminated with light of 2eV [ BHU 1998]
  • a)2.6 V
  • b) 3.6 V
  • c)0.8 V
  • d)1.4 V
Q.25
Photoelectric effect supports
  • a) Newton's corpuscular nature of light
  • b) Huyen's wave theory of light
  • c)Maxwell's electromagnetic theory of light
  • d)Einstein's quantum theory of light
Q.26
The photoelectrons emitted from a metal surface are such that
  • a) They are all at rest
  • b) They all have the same energy
  • c)Their energy varies from 0 to ∞
  • d)Their energy varies from 0 to a finite maximum value
Q.27
Work function of tungsten and sodium are 4.4 eV and 2.3eV respectively. If threshold wave length of sodium is 5460Å , then the threshold wavelength of tungsten is [ Raj. PMT 1993]
  • a) 11360Å
  • b) 8000Å
  • c) 6000Å
  • d) 2854Å
Q.28
Light of frequency 1.5 times the threshold frequency is incident on photosensitive material. If the frequency is halved and intensity is doubled, the photo current becomes [ EAMCET 1991]
  • a)Quadrupled
  • b) Doubled
  • c)Halved
  • d)Zero
Q.29
In Einstein's photo-electric equationEkin=hν - φ Ekin stands for [ MPPMT 1997]
  • a) kinetic energy of all the emitted electrons
  • b) mean kinetic energy of the emitted electrons
  • c)maximum kinetic energy of the emitted electrons
  • d)minimum kinetic energy of the emitted electrons
Q.30
When photons of energy hν fall on a photo sensitive metallic surface ( work function hνo) electrons emitted from the metallic surface. Then
  • a) All ejected electrons have same kinetic energy equal to hν - hν0
  • b)The maximum kinetic energy is equal to hν - hν0
  • c)The maximum kinetic energy hν
  • d)The kinetic energy of ejected electron is hνo
0 h : 0 m : 1 s