Physics NEET MCQ - Particle Nature Of Light Mcq - Quiz-2 - MCQGeeks.com

Q.1

When photons of energy hν fall on an aluminium plate ( of work function Φ), photoelectrons of maximum kinetic energy of K are ejected. If the frequency of the radiation is doubled then ejected photoelectrons will be.. [ CBSE-PMT 2006]

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a)2K
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b)K
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c)K + hν
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d)K + Φ

Q.2

The X-rays cannot be diffracted by means of an ordinary grating because of .. [ CBSE-PMT 1997]

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a) high speed
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b) short wave length
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c)large wave length
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d)none of these

Q.3

The wave length associated with an electron accelerated through a potential difference of 100V, is of the order of .. [ CBSE-PMT 1996]

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a) 1000 Å
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b) 100 Å
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c)10.5 Å
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d)1.2 Å

Q.4

In the Davisson and Germar experiment, the velocity of electrons emitted from the electron gun can be increased by[ CBSE-PMT 2011]

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a) increasing the potential difference between the anode and filament
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b) increasing the filament current
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c) decreasing the filament current
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d) decreasing the potential difference between the anode and filament

Q.5

The number of photo electrons emitted for light of frequency ν ( higher than the threshold frequency ν0 is proportional to [ CBSE - PMT 2009]

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a) Threshold frequency ( ν0
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b) Intensity of light
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c)Frequency of light ν
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d)ν - ν0

Q.6

Light of two different frequencies whose photos have energies 1eV and 2.5eV respectively illuminate a metallic surface whose work function is 0.5eV successively. Ratio of maximum speeds of emissions will be [ CBSE-PMT 2011]

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a)1:4
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b) 1:2
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c)1:1
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d)1:5

Q.7

A beam of cathode rays is sunjected to crossed Electric field(E) and Magnetic field (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by [ CBSE-PMT 2010]V is the potentia; difference between cathode and anode

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a)
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b)
0%
c)
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d)

Q.8

The work function of a surface of a photosensitive material is 6.2 eV. The wave length of incident radiation for which the stopping potential is 5V lies in the [ CBSE-PMT 2008]

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a)Ultraviolet region
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b) Visible region
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c)Inferred region
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d)X-ray region

Q.9

A photo-cell employ photoelectric effect to convert [ CBSE-PMT 2006]

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a) Change in the intensity of illumination into a change in photoelectric current
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b) Change in the intensity of illumination into a change in the work function of the photocathode
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c)change in the frequency of light into a change in the electric current
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d)change in the frequency of light into a change in electric voltage

Q.10

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]

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a) 2.4V
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b) -1.2V
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c)-2.4V
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d)1.2V

Q.11

Photoelectric work function of a metal is 1eV. Light of wave length λ=3000 Å falls on it. The photo electron come out with velocity [ CBSE-PMT 1991]

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a) 10 m/sec
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b) 102 m/sec
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c) 104 m/sec
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d) 106

Q.12

The threshold frequency for photoelectric effect on sodium corresponds to a wavelength of 5000 Å its work function is [ CBSE-PMT 1988]

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a)4 ×10-19 J
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b) 1 J
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c)2× 10-19 J
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d)3 ×10-19 J

Q.13

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]

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a) increase by 2 times
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b) decrease by 2 times
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c)decrease by 4 times
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d)increase by 4 times

Q.14

A particle of mass 1mg has the same wave length as an electron moving with velocity of 3×106 ms-The velocity of the particle is [ CBSE-PMT 2008] mass of electron=9.1×10-31 kg

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a)2.7×10-18 m/s
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b) 9×10-2 m/s
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c)3×10-31m/s
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d)2.7×10-21m/s

Q.15

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]

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a) 3×1016
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b) 9×1015
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c) 3×1019
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d) 9×1017

Q.16

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]

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a)excitation of electons in the atoms
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b) Collision between the atoms of the gas
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c)Collision between the charges particles emitted from the cathode and the atoms of the gas
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d)Collision between different electrons of atoms of the gas

Q.17

In discharge tube ionization of enclosed gas is produced due to collisions between [ CBSE-PMT 2006]

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a) negative electrons and neutral atoms / molecules
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b) photons and neutral atoms/ molecule
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c)neutral gas atoms / molecules
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d)positive ions and neutral atoms/molecule

Q.18

Photoelectric emission occurs only when the incident light has more than a certain minimum [ CBSE-PMT 2011]

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a) power
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b) wavelength
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c)intensity
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d)frequency

Q.19

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]

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a) infra-red waves
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b) X-rays
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c) Visible light rays
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d) radio waves

Q.20

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]

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a)1.00
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b) 1.02
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c)1.04
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d)0.98

Q.21

A photoelectric cell is illuminated by a point source of light 1m away. When the source is shifted to 2m then [ CBSE-PMT 2003]

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a) number of electrons emitted is a quarter of initial number
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b) each emitted electron carries one quarter of the initial energy
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c)number of electrons emitted is half the initial number
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d)each emitted electron carries half the initial energy

Q.22

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]

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a) 1:2
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b) 2:1
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c)4:1
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d)1:4

Q.23

A radio transmitter operates at a frequency 880kHz and a power of 10kW. the number of photons emitted per second is .. [ CBSE-PMT 1990]

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a) 1.72×1031
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b) 1.327×1025
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c) 1.327×1037
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d) 1.327×1045

Q.24

The wave length of 1keV photon is 1.24×10-9m. What is the frequency of 1MeV photon?

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a)1.24×1015
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b) 2.4×1020
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c)1.24×1018
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d)2.4×1023

Q.25

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]

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a)
0%
b)
0%
c)
0%
d)

Q.26

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

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a)100Po
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b) 400Po
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c)Po/400
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d)Po

Q.27

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

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a)none
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b) A only
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c)A and B only
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d)All three metals

Q.28

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]

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a) 8
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b) 16
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c) 2
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d) 4

Q.29

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]

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a)2V
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b) 3V
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c)5V
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d)1V

Q.30

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]

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a) I1=I2
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b) I1 < I2
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c)I1 > I2
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d)I1< I2<2I1

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