# MCQ Question for Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter

Refer to MCQ Class 12 Dual Nature of Radiation and Matter provided below which is an important chapter in Class 12 Physics. Students should go through the MCQs questions for Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter with answers given below so that they are able to understand the complete topic properly. It’s important to understand the entire chapter by reading Class 12 Physics Notes also. Also, refer to MCQ Questions for Class 12 Physics for all chapters.

## MCQ on Dual Nature of Radiation and Matter Class 12 Physics PDF with Answers

All multiple choice questions with solutions provided below have been developed based on the latest syllabus and examination pattern issued for class 12 by CBSE and NCERT. As Dual Nature of Radiation and Matter is a very important and scoring chapter in Physics Class 12, therefore, the students should carefully learn the questions and answers given below which will help them to get better scores in upcoming examinations for class 12th.

Question. X-ray will not show the phenomenon of :
(a) interference
(b) deflection by electric field
(c) diffraction
(d) superposition

B

Question. Which one of the following is not dependent on the intensity of incident photon in a photoelectric experiment ?
(a) work function of the surface
(b) kinetic energy of photo-electron
(c) stopping potential
(d) amount of photo-electric current

B

Question. The kinetic energy of an electron, which is accelerated in the potential difference of 100 V, is :
(a) 1.6 × 10–10 J
(b) 1.6 × 108 J
(c) 1.6 × 10–17 J
(d) 1.6 × 10–18 J

C

Question. When cathode rays strike a metal target of high melting point with a very high velocity then which of the following are produced ?
(a) g-waves
(b) Ultrasonic
(c) X-rays
(d) a-rays

C

Question Particle nature and wave nature of electromagnetic waves and electrons can be represented by :
(a) photoelectricity and electron microscopy
(b) light is refracted and diffracted
(c) X-rays is diffracted, reflected by thick metal sheet
(d) electrons have small mass, deflected by the metal sheet.

A

Question. The surface of zone material is radiated in turn by waves of l = 350 nm and 540 nm respectively.
The ratio of the stopping potential in the two cases is 2 : 1. The work function of the material is
(a) 4.20 eV
(b) 0.15 eV
(c) 2.10 eV
(d) 1.05 eV

D

Question. Light of wavelength 4000 Åis incident on a metal plate whose work function is 2eV. What is maximum kinetic energy of emitted photoelectron?
(a) 0.5 eV
(b) 1.1 eV
(c) 2.0 eV
(d) 1.5 eV

B

Question. A laser beam is used for carrying out surgery because it
(a) is highly monochromatic
(b) is highly coherent
(c) is highly directional
(d) can be sharply focussed

D

Question. A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, its kinetic energy will be
(a) 1840 keV
(b) 1/1840 keV
(c) 1keV
(d) 920 V

C

Question. If an electron and a photon propagate in the form of waves having the same wavelength, it implies that they have the same
(a) energy
(b) momentum
(c) velocity
(d) angular momentum

B

Question. Characteristic X-rays are produced due to
(a) transfer of momentum in collision of electrons with target atoms
(b) transition of electrons from higher to lower electronic orbits of an atom
(c) heating of the target
(d) transfer of energy in collision of electrons with atoms in the target.

B

Question. A photon of energy 4 eV is incident on a metal surface whose work function is 2eV. The minimum reverse potential to be applied for stopping the emission of electrons is
(a) 2V
(b) 4V
(c) 6V
(d) 8V

A

Question. Solid targets of different elements are bombarded by highly energetic electron beams. The frequency (f) of the characteristic X-rays emitted from different targets varies with atomic number Z as
(a) f μ Z
(b) f μ Z2
(c) f μ Z
(d) f μ Z3/2

B

Question. Hard X-rays for the study of fractures in bones should have a minimum wavelength of 1011 m.
The accelerating voltage for electrons in X-ray machine should be
(a) < 124.2 kV
(b) > 124.2 kV
(c) Between 60 kV and 70 kV
(d) = 100 kV

A

Question. In photoelectric effect, the electrons are ejected from metals if the incident light has a certain minimum
(a) Wavelength
(b) Frequency .
(c) Amplitude
(d) Angle of incidence

B

Question. The stopping potential doubles when the frequency of the incident light changes from n to 3v/2. Then the work function of the metal must be
(a) hν/2
(b) hν
(c) 2hν
(d) none of the above

A

Question. The force on a hemisphere of radius 1 cm if a parallel beam of monochromatic light of wavelength 500 nm. falls on it with an intensity of 0.5 W/cm2, striking the curved surface in a direction which is perpendicular to the flat face of the hemisphere is (assume the collisions to be perfectly inelastic)
(a) 5.2 × 10–13 N
(b) 5.2 × 10–12 N
(c) 5.22 × 10–9 N
(d) zero

C

Question. A 15.0 eV photon collides with and ionizes a hydrogen atom. If the atom was originally in the ground state (ionization potential =13.6 eV), what is the kinetic energy of the ejected electron?
(a) 1.4 eV
(b) 13.6 eV
(c) 15.0 eV
(d) 28.6 eV

A

Question. 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
(a)  B2/2VE2
(b) 2VB2/E2
(c) 2VE2/B2
(d) E2/2VB2
(Where V is the potential difference between cathode and anode)

D

Question. In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of
(a) collisions between the charged particles emitted from the cathode and the atoms of the ga
(b) collision between different electrons of the atoms of the gas
(c) excitation of electrons in the atoms
(d) collision between the atoms of the gas.

A

Question. In a discharge tube ionization of enclosed gas is produced due to collisions between
(a) neutral gas atoms/molecules
(b) positive ions and neutral atoms/molecules
(c) negative electrons and neutral atoms/molecules
(d) photons and neutral atoms/molecules.

C

Question. J.J. Thomson’s cathode-ray tube experiment demonstrated that
(a) cathode rays are streams of negatively charged ions
(b) all the mass of an atom is essentially in the nucleus
(c) the e/m of electrons is much greater than the e/m of protons
(d) the e/m ratio of the cathode-ray particles changes when a different gas is placed in the discharge tube

C

Question. Which of the following is not the property of cathode rays ?
(a) It produces heating effect.
(b) It does not deflect in electric field.
(d) It produces fluorescence.

B

Question. Who evaluated the mass of electron indirectly with help of charge?
(a) Thomson
(b) Millikan
(c) Rutherford
(d) Newton

A

Question. In a discharge tube at 0.02 mm, there is formation of
(a) Crooke’s dark space
(c) both space partly
(d) none of these.

A

Question. In which of the following, emission of electrons does not take place
(a) thermionic emission
(b) X-rays emission
(c) photoelectric emission
(d) secondary emission

B

Question. Thermions are
(a) protons
(b) electrons
(c) photons
(d) positrons

B

Question. 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 :
(a) V0/2
(b) V0
(c) 4V0
(d) 2V0

B

Question. Photoelectric emission occurs only when the incident light has more than a certain minimum
(a) power
(b) wavelength
(c) intensity
(d) frequency

D

Question. 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
(a) 1.8 V
(b) 1.3 V
(c) 0.5 V
(d) 2.3 V

C

Question. 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 2I, the number of emitted electrons and their maximum kinetic energy are respectively
(a) N and 2T
(b) 2N and T
(c) 2N and 2T
(d) N and T

B

Question. The number of photo electrons emitted for light of a frequency u (higher than the threshold frequency ν0) is proportional to
(a) threshold frequency (ν0)
(b) intensity of light
(c) frequency of light (ν)
(d) ν – ν0

B

Question. A 5 watt source emits monochromatic light of wavelength 5000 Å. 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
(a) 8
(b) 16
(c) 2
(d) 4

D

Question. A photocell employs photoelectric effect to convert
(a) change in the frequency of light into a change in the electric current
(b) change in the frequency of light into a change in electric voltage
(c) change in the intensity of illumination into a change in photoelectric current
(d) change in the intensity of illumination into a change in the work function of the photocathode.

C

Question. A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then
(a) each emitted electron carries one quarter of theinitial energy
(b) number of electrons emitted is half the initial number
(c) each emitted electron carries half the initial energy
(d) number of electrons emitted is a quarter of the initial number.

D

Question. When ultraviolet rays incident on metal plate then photoelectric effect does not occur, it occurs by incidence of
(a) infrared rays
(b) X-rays
(d) micro wave.

B

Question. 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
(a) remain same
(b) four times
(c) two times
(d) one-fourth.

B

Question. As the intensity of incident light increases
(a) kinetic energy of emitted photoelectrons increases
(b) photoelectric current decreases
(c) photoelectric current increases
(d) kinetic energy of emitted photoelectrons decreases.

C

Question. Which of the following statement is correct?
(a) The photocurrent increases with intensity of light.
(b) The stopping potential increases with increase of incident light.
(c) The current in photocell increases with increasing frequency.
(d) The photocurrent is proportional to the applied voltage.

A

Question. Number of ejected photoelectrons increases with increase
(a) in intensity of light
(b) in wavelength of light
(c) in frequency of light
(d) never.

A

Question. The cathode of a photoelectric cell is changed such that the work function changes from W1 to W2 (W2 > W1). If the current before and after changes are I1 and I2, all other conditions remaining unchanged, then (assuming hu > W2)
(a) I1 = I2
(b) I1 < I2
(c) I1 > I2
(d) I1 < I2 < 2I1

A

Question. As the intensity of incident light increases
(a) kinetic energy of emitted photoelectrons increases
(b) photoelectric current decreases
(c) photoelectric current increases
(d) kinetic energy of emitted photoelectrons decreases.

C

Question. The cathode of a photoelectric cell is changed such that the work function changes from W1 to W2 (W2 > W1). If the current before and after changes are I1 and I2, all other conditions remaining unchanged, then (assuming hu > W2)
(a) I1 = I2
(b) I1 < I2
(c) I1 > I2
(d) I1 < I2 < 2I1

A

Question. In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of
(a) collisions between the charged particles emitted from the cathode and the atoms of the gas
(b) collision between different electrons of the atoms of the gas
(c) excitation of electrons in the atoms
(d) collision between the atoms of the gas.

A

Question. In a discharge tube ionization of enclosed gas is produced due to collisions between
(a) neutral gas atoms/molecules
(b) positive ions and neutral atoms/molecules
(c) negative electrons and neutral atoms/molecules
(d) photons and neutral atoms/molecules.

C

Question. J.J. Thomson’s cathode-ray tube experiment demonstrated that
(a) cathode rays are streams of negatively charged ions
(b) all the mass of an atom is essentially in the nucleus
(c) the e/m of electrons is much greater than the e/m of protons
(d) the e/m ratio of the cathode-ray particles changes when a different gas is placed in the discharge tube

C

Question. Which of the following is not the property of cathode rays ?
(a) It produces heating effect.
(b) It does not deflect in electric field.
(d) It produces fluorescence.

B

Question. Which of the following statement is correct?
(a) The photocurrent increases with intensity of light.
(b) The stopping potential increases with increase of incident light.
(c) The current in photocell increases with increasing frequency.
(d) The photocurrent is proportional to the applied voltage.

A

Question. Number of ejected photoelectrons increases with increase
(a) in intensity of light
(b) in wavelength of light
(c) in frequency of light
(d) never.

A

Question. Who evaluated the mass of electron indirectly with help of charge?
(a) Thomson
(b) Millikan
(c) Rutherford
(d) Newton

A

Question. In a discharge tube at 0.02 mm, there is formation of
(a) Crooke’s dark space
(c) both space partly
(d) none of these.

A

Question. In which of the following, emission of electrons does not take place
(a) thermionic emission
(b) X-rays emission
(c) photoelectric emission
(d) secondary emission

B

Question. Thermions are
(a) protons
(b) electrons
(c) photons
(d) positrons.

B

Question. 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
(a) 1.8 V
(b) 1.3 V
(c) 0.5 V
(d) 2.3 V

C

Question. A 5 watt source emits monochromatic light of wavelength 5000 Å. 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
(a) 8
(b) 16
(c) 2
(d) 4

D

Question. A photocell employs photoelectric effect to convert
(a) change in the frequency of light into a change in the electric current
(b) change in the frequency of light into a change in electric voltage
(c) change in the intensity of illumination into a change in photoelectric current
(d) change in the intensity of illumination into a change in the work function of the photocathode.

C

Question. The photoelectric threshold wavelength of silver is 3250 × 10–10 m. The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536 × 10–10 m is [Given h = 4.14 × 10–15 eV s and c = 3 × 108 m s–1]
(a) ≈ 0.6 × 106 m s–1
(b) ≈ 61 × 103 m s–1
(c) ≈ 0.3 × 106 m s–1
(d) ≈ 6 × 105 m s–1

A,D

Question. A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then
(a) each emitted electron carries one quarter of the initial energy
(b) number of electrons emitted is half the initial number
(c) each emitted electron carries half the initial energy
(d) number of electrons emitted is a quarter of the initial number.

D

Question. When ultraviolet rays incident on metal plate then photoelectric effect does not occur, it occurs by incidence of
(a) infrared rays
(b) X-rays
(d) micro wave.

B

Question. 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
(a) remain same
(b) four times
(c) two times
(d) one-fourth.

B

Question. 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 :
(a) V0/2
(b) V0
(c) 4V0
(d) 2V0

B

Question. Photoelectric emission occurs only when the incident light has more than a certain minimum
(a) power
(b) wavelength
(c) intensity
(d) frequency

D

Question. 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?
(a) Doubled
(b) Four times
(c) One-fourth
(d) Zero

D

Question. The work function of a photosensitive material is 4.0 eV. The longest wavelength of light that can cause photon emission from the substance is (approximately)
(a) 3100 nm
(b) 966 nm
(c) 31 nm
(d) 310 nm

D

Question. When the light of frequency 2u0 (where u0 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 5u0, the maximum velocity of electrons emitted from the same plate is v2. The ratio of v1 to v2 is
(a) 1 : 2
(b) 1 : 4
(c) 4 : 1
(d) 2 : 1

A

Question. A photoelectric surface is illuminated successively by monochromatic light of wavelength l and l/2. 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)
(a) 2hc/λ
(b) hc/3λ
(c) hc/2λ
(d) hc /λ

C

Question. A certain metallic surface is illuminated with monochromatic light of wavelength, l. The stopping potential for photoelectric current for this light is 3V0. If the same surface is illuminated with light of wavelength 2l, the stopping potential is V0. The threshold wavelength for this surface for photoelectric effect is
(a) λ/4
(b) λ/6
(c) 6l
(d) 4l

D

Question. When the energy of the incident radiation is increased by 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
(a) 0.65 eV
(b) 1.0 eV
(c) 1.3 eV
(d) 1.5 eV

B

Question. 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
(a) 1 : 4
(b) 1 : 2
(c) 1 : 1
(d) 1 : 5

B

Question. 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 2I, the number of emitted electrons and their maximum kinetic energy are respectively
(a) N and 2T
(b) 2N and T
(c) 2N and 2T
(d) N and T

B

Question. The threshold frequency for a photosensitive 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 photoelectron emission is nearly
(a) 1 V
(b) 2 V
(c) 3 V
(d) 5 V

B

Question. 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 200 nm falls on it, must be
(a) 2.4 V
(b) –1.2 V
(c) –2.4 V
(d) 1.2 V

B

Question. 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
(a) Infrared region
(b) X-ray region
(c) Ultraviolet region
(d) Visible region.

C

Question. When photons of energy hu fall on an aluminium 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
(a) K + hu
(b) K + E0
(c) 2K
(d) K

A

Question. Photons with energy 5 eV are incident 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
(a) +3 V
(b) +4 V
(c) –1 V
(d) –3 V

D

Question. When a metallic surface is illuminated with radiation of wavelength l, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2l, the stopping potential is V/4. The threshold wavelength for the metallic surface is
(a) 5/2 λ
(b) 3λ
(c) 4λ
(d) 5λ

B

Question. 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 Å is/are
(a) A only
(b) A and B only
(c) all the three metals
(d) none.

B

Question. The number of photo electrons emitted for light of a frequency u (higher than the threshold frequency u0) is proportional to
(a) threshold frequency (u0)
(b) intensity of light
(c) frequency of light (u)
(d) u – u0

B

Question. A photosensitive metallic surface has work function, hu0. If photons of energy 2hu0 fall on this surface, the electrons come out with a maximum velocity of 4 × 106 m/s. When the photon energy is increased to 5hu0, then maximum velocity of photoelectrons will be
(a) 2 × 107 m/s
(b) 2 × 106 m/s
(c) 8 × 106 m/s
(d) 8 × 105 m/s

C

Question. The value of Planck’s constant is
(a) 6.63 × 10–34 J/sec
(b) 6.63 × 10–34 kg m2/sec
(c) 6.63 × 10–34 kg m2
(d) 6.63 × 10–34 J sec