Dual Nature of Radiation and Matter · Physics · NEET
MCQ (Single Correct Answer)
1
De-Broglie wavelength of an electron orbiting in the $n=2$ state of hydrogen atom is close to
(Given Bohr radius $=0.052 \mathrm{~nm}$ )
NEET 2025
2
Which of the following options represent the variation of photoelectric current with property of light shown on the x-axis?
NEET 2025
3
A photon and an electron (mass $m$ ) have the same energy $E$. The ratio ( $\lambda_{\text {photon }} / \lambda_{\text {electron }}$ ) of their de Broglie wavelengths is: ( $c$ is the speed of light)
NEET 2025
4
An electron and an alpha particle are accelerated by the same potential difference. Let $$\lambda_e$$ and $$\lambda_\alpha$$ denote the de-Broglie wavelengths of the electron and the alpha particle, respectively, then:
NEET 2024 (Re-Examination)
5
If $$\phi$$ is the work function of photosensitive material in $$\mathrm{eV}$$ and light of wavelength of numerical value $$\lambda=\frac{h c}{e}$$ metre, is incident on it with energy above its threshold value at an instant then the maximum kinetic energy of the photo-electron ejected by it at that instant (Take $$h$$-Plank's constant, $$c$$-velocity of light in free space) is (in SI units):
NEET 2024 (Re-Examination)
6
The graph which shows the variation of $$\left(\frac{1}{\lambda^2}\right)$$ and its kinetic energy, $$E$$ is (where $$\lambda$$ is de Broglie wavelength of a free particle):
NEET 2024
7
If $$c$$ is the velocity of light in free space, the correct statements about photon among the following are:
A. The energy of a photon is $$E=h v$$.
B. The velocity of a photon is $$c$$.
C. The momentum of a photon, $$p=\frac{h v}{c}$$.
D. In a photon-electron collision, both total energy and total momentum are conserved.
E. Photon possesses positive charge.
Choose the correct answer from the options given below:
NEET 2024
8
The de Broglie wavelength associated with an electron, accelerated by a potential difference of 81 V is given by:
NEET 2023 Manipur
9
The maximum kinetic energy of the emitted photoelectrons in photoelectric effect is independent of:
NEET 2023 Manipur
10
The work functions of Caesium $$(\mathrm{Cs})$$, potassium $$(\mathrm{K})$$ and Sodium (Na) are $$2.14 ~\mathrm{eV}, 2.30 ~\mathrm{eV}$$ and $$2.75 ~\mathrm{eV}$$ respectively. If incident electromagnetic radiation has an incident energy of $$2.20 ~\mathrm{eV}$$, which of these photosensitive surfaces may emit photoelectrons?
NEET 2023
11
The minimum wavelength of $$X$$-rays produced by an electron accelerated through a potential difference of $$V$$ volts is proportional to :
NEET 2023
12
The light rays having photons of energy 4.2 eV are falling on a metal surface having a work function of 2.2 eV. The stopping potential of the surface is
NEET 2022 Phase 2
13
The threshold frequency of a photoelectric metal is v0. If light of frequency 4v0 is incident on this metal, then the maximum kinetic energy of emitted electrons will be :
NEET 2022 Phase 2
14
When two monochromatic lights of frequency, v and $${v \over 2}$$ are incident on a photoelectric metal, their stopping potential becomes $${{{V_s}} \over 2}$$ and Vs respectively. The threshold frequency for this metal is
NEET 2022 Phase 1
15
The number of photons per second on an average emitted by the source of monochromatic light of wavelength 600nm, when it delivers the power of 3.3 $$\times$$ 10$$-$$3 watt will be : (h = 6.6 $$\times$$ 10$$-$$34 Js)
NEET 2021
16
An electromagnetic wave of wavelength '$$\lambda$$' is incident on a photosensitive surface of negligible work function. If 'm' mass is of photoelectron emitted from the surface has de-Broglie wavelength $$\lambda$$d, then :
NEET 2021
17
Light of frequency 1.5 times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled?
NEET 2020 Phase 1
18
Light with an average flux of 20 W/cm2 falls on a non-reflecting surface at normal incidence having surface area 20 cm2. The energy received by the surface during time span of 1 minute is :
NEET 2020 Phase 1
19
An electron is accelerated from rest through a potential difference of V volt. If the de-Broglie wavelength of the electron is 1.227 $$ \times $$ 10-2 nm, the potential difference is :
NEET 2020 Phase 1
20
An electron is accelerated through a potential difference of 10,000 V. Its de Broglie wavelength is (nearly) : (me = 9 $$ \times $$ 10–31 kg)
NEET 2019
21
An electron of mass m with an initial velocity
$$\overrightarrow v = {v_0}\widehat i$$ (v0 > 0)
enters an electric field
$$\overrightarrow E = - {\overrightarrow E _0}\widehat i$$
(E0
= constant > 0) at t = 0. If $$\lambda $$0
is its de-Broglie wavelength initially, then its
de- Broglie wavelength at time t is
NEET 2018
22
When the light of frequency 2$${\upsilon _0}$$
(where $${\upsilon _0}$$
is
threshold frequency), is incident on a metal
plate, the maximum velocity of electrons
emitted is v1
. When the frequency of the
incident radiation is increased to 5$${\upsilon _0}$$
, the
maximum velocity of electrons emitted from
the same plate is v2
. The ratio of v1
to v2
is
NEET 2018
23
The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (kelvin) and mass m, is
NEET 2017
24
Photons with energy 5 eV are incifent on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is
NEET 2016 Phase 2
25
Electrons of mass m with de-Broglie wavelength $$\lambda $$ fall on the target in an X-ray tube. The cutoff wavelength ($$\lambda $$0) of the emitted X-ray is
NEET 2016 Phase 2
26
An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is
NEET 2016 Phase 1
27
When a metallic surface is illuminated with radiation of wavelength $$\lambda $$, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2 $$\lambda $$, the stopping potential is $${V \over 4}$$. The threshold wavelength for the metallic surface is
NEET 2016 Phase 1
28
Light of wavelength 500 nm is incifent on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is
AIPMT 2015
29
A photoelectric surface is illuminated successively by monochromatic light of wavelength $$\lambda $$ and If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is
(h = Planck's constant, C = speed of light)
(h = Planck's constant, C = speed of light)
AIPMT 2015
30
Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?
AIPMT 2015 Cancelled Paper
31
A certain metallic surface is illuminated with monochromatic light of wavelength, $$\lambda .$$ The stopping potential for photo-electric current for this light is 3V0. If the same surface is illuminated with light of wavelength 2 $$\lambda $$, the stopping potential is V0. The threshold wavelength for this surface for photo-electric effect is
AIPMT 2015 Cancelled Paper
32
If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de Broglie wavelength of the particle is
AIPMT 2014
33
When the energy of the incident radiation is increased nby 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is
AIPMT 2014
34
The de-broglie wavelength of neutrons in thermal equilibrium at temperature T is
NEET 2013 (Karnataka)
35
A source of light is placed at a distance of 50 cm from a photo cell and the stopping potential is found to be V0. If the distance between the light source and photo cell is made 25 cm, the new stopping potential will be :
NEET 2013 (Karnataka)
36
A parallel beam of fast moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct ?
NEET 2013
37
For photoelectric emission from certain metal the cutoff frequency is $$\upsilon $$. If radiation of frequency 2$$\upsilon $$ impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)
NEET 2013
38
The wavelength $$\lambda $$e of an electron and $$\lambda $$p of a photon of same energy E are related by
NEET 2013
39
Two radiations of photons energies 1 eV and 2.5 eV, successively illuminate a photosensitive metallic surface of work function 0.5 eV. The ratio of the maximum speeds of the emitted electrons is
AIPMT 2012 Mains
40
If the momentum of an electron is changed by P, then the de Broglie wavelength associated with changes by 0.5%. The initial momentum of electron will be
AIPMT 2012 Mains
41
An $$\alpha $$-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m2. The de Broglie wavelength associated with the particle will be
AIPMT 2012 Prelims
42
Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is
AIPMT 2012 Prelims
43
A 200 W sodium street lamp emits yellow light of wavelength 0.6 $$\mu $$m. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
AIPMT 2012 Prelims
44
The threshold frequency for a photosensitive metal is 3.3 $$ \times $$ 1014 Hz. If light of frequency 8.2 $$ \times $$ 1014 Hz is incident on this metal, the cut- off voltage for the photoelectron emission is nearly
AIPMT 2011 Mains
45
Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds of emitted electrons will be
AIPMT 2011 Prelims
46
In photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. The corresponding stopping potential is
AIPMT 2011 Prelims
47
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
AIPMT 2011 Prelims
48
In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by
AIPMT 2011 Prelims
49
Photoelectric emission occurs only when the incident light has more than a certain minimum
AIPMT 2011 Prelims
50
The electron in the hydrogen atom jumps from excited state (n = 3) to its ground state (n = 1) and the photons thus emitted irradiate a photosensitive material. If the work function of the material is 5.1 eV, the stopping potential is estimated to be (the energy of the electron in nth state En = $${{ - 13.6} \over {{n^2}}}eV$$)
AIPMT 2010 Mains
51
When monochromatic radiation of intensity $$I$$ falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are N and T respectively. If the intensity of radiation is 2$$I$$, the number of emitted electrons and their maximum kinetic energy are respectively
AIPMT 2010 Mains
52
The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work functions 5.01 eV, when ultraviolet light of 200 nm falls on it, must be
AIPMT 2010 Prelims
53
A source S1 is producing, 1015 photons per second of wavelength 5000 $$\mathop A\limits^ \circ $$. Another source S2 is producing 1.02 $$ \times $$ 1015 photons per second of wavelength 5100 $$\mathop A\limits^ \circ $$. Then, (power of S2)/(power of S1) is equal to
AIPMT 2010 Prelims
54
A beam of cathode rays is subjected to crossed electric (E) and magnetic fields (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by
(Where V is the potential difference between cathode and anode)
(Where V is the potential difference between cathode and anode)
AIPMT 2010 Prelims
55
The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement?
AIPMT 2009
56
Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per sec. on the average at a target irradiated by this beam is
AIPMT 2009
57
The number of photo electrons emitted for light of a frequency $$\upsilon $$ (higher than the threshold frequency $${\upsilon _0}$$) is proportional to
AIPMT 2009
58
In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of
AIPMT 2008
59
A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 $$ \times $$ 106 m s$$-$$1. The velocity of the particle is
AIPMT 2008
60
The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the
AIPMT 2008
61
Monochromatic light of frequency 6.0 $$ \times $$ 1014 Hz is produced by a laser. The power emitted is 2 $$ \times $$ 10$$-$$3 W. The number of photons emitted, on the average, by the source per second is
AIPMT 2007
62
A beam of electron passes undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off, and the same magnetic field is maintained, the electrons move
AIPMT 2007
63
A 5 watt source emits monochromatic light of wavelength 5000 $$\mathop A\limits^ \circ $$. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 m, the number of photoelectrons liberated will be reduced by a factor of
AIPMT 2007
64
The momentum of a photon of energy 1 MeV in kg m/s will be
AIPMT 2006
65
In a discharge tube ionization of enclosed gas is produced due to collisions between
AIPMT 2006
66
When photons of energy h$$\upsilon $$ fall on an aluminimum plate (of work function E0), photoelectrons of maximum kinetic energy K are ejected. If the frequency of radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be
AIPMT 2006
67
A photocell employs photoelectric effect to convert
AIPMT 2006
68
The work functions for metals A, B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein's equation the metals which will emit photoelectrons for a radiation of wavelength 4100 $$\mathop A\limits^ \circ $$ is/are
AIPMT 2005
69
A photosensitive metallic surface has work function, h$$\upsilon $$0. If photons of energy $$2h{\upsilon _0}$$ fall on this surface, the electrons come out with a maximum velocity of 4 $$ \times $$ 106 m/s. When the photon energy is increased to 5 h$$\upsilon $$0, then maximum velocity of photoelectrons will be
AIPMT 2005
70
According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is
AIPMT 2004
71
A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then
AIPMT 2003
72
J.J. Thomson's cathode-ray tube experiment demonstrated that
AIPMT 2003
73
Which of the following is not the property of cathode rays ?
AIPMT 2002
74
When ultraviolet rays incident on metal plate then photoelectric effect does not occur, it occurs by incidence of
AIPMT 2002
75
The value of Planck's constant is
AIPMT 2002
76
If particles are moving with same velocity, then which has maximum de Broglie wavelength?
AIPMT 2002
77
A photo-cell is illuminated by a source of light, which is placed at a distance d from the cell. If the distance become d/2, then number of electrons emitted per second, will be
AIPMT 2001
78
In Thomson mass spectrograph $$\overrightarrow E \bot \overrightarrow B $$ then the velocity of electron beam will be
AIPMT 2001
79
Which one among the following shows particle nature of light?
AIPMT 2001
80
By photoelectric effect, Einstein proved
AIPMT 2000
81
Who evaluated the mass of electron infirectly with help of charge
AIPMT 2000