# MCQs For NCERT Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter

Please refer to the MCQ Questions for Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter with Answers. The following Dual Nature of Radiation and Matter Class 12 Physics MCQ Questions have been designed based on the latest syllabus and examination pattern for Class 12. Our experts have designed MCQ Questions for Class 12 Physics with Answers for all chapters in your NCERT Class 12 Physics book.

## Dual Nature of Radiation and Matter Class 12 MCQ Questions with Answers

See below Dual Nature of Radiation and Matters Class 12 Physics MCQ Questions, solve the questions and compare your answers with the solutions provided below.

Question. The de-Broglie wavelength of an electron moving in the nth Bohr orbit of radius r is given by
(a) 2πr/n
(b) nπr
(c) nr/2π
(d) nr/π

A

Question. Which of the following shows particle nature of light?
(a) Refraction
(b) Interference
(c) Polarization
(d) Photoelectric effect

B

Question. If the energy of a photon is 10 eV, then its momentum is
(a) 5.33 × 10–23 kg m/s
(b) 5.33 × 10–25 kg m/s
(c) 5.33 × 10–29 kg m/s
(d) 5.33 × 10–27 kg m/s

D

Question. In an electron gun the control grid is given a negative potential relative to cathode in order to
(a) decelerate electrons
(b) repel electrons and thus to control the number of electrons passing through it
(c) to select electrons of same velocity and to converge them along the axis.
(d) to decrease the kinetic energy of electrons

B

Question. Light of frequency v falls on a material of threshold frequency v0. Maximum kinetic energy of emitted electron is proportional to
(a) v–v0
(b) v
(b) √v – v0
(d) v0

A

Question. The maximum velocity of an electron emitted by light of wavelength λ incident on the surface of a metal of work function Φ is

C

Question. In case of electrons and photons having the same wavelength. What is same for them?
(a) Energy
(b) Velocity
(c) Momentum
(d) Angular momentum

C

30. Two insulating plates are both uniformly charged in such a way that the potential difference between them is V2 – V1 = 20 V. (i.e., plate 2 is at a higher potential). The plates are separated by d = 0.1 m and can be treated as infinitely large. An electron is released from rest on the inner surface of plate 1. What is its speed when it hits plate 2? (e = 1.6 × 10–19 C, me = 9.11 × 10–31 kg)

(a) 2.65 × 106 m/s
(b) 7.02 × 1012 m/s
(c) 1.87 × 106 m/s
(d) 32 × 10–19 m/s

A

Question. A steel ball of mass m is moving with a kinetic energy K. The de-Broglie wavelength associated with the ball is

C

Question. An X-ray tube with Cu target is operated at 25 kV. The glancing angle for a NaCl. Crystal for the Cu ka line is 15.8°. Find the wavelength of this line. (d for NaCl = 2.82 Å, h = 6.62 × 10–27 erg-sec)
(a) 3.06 Å
(b) 1.53 Å
(c) 0.75 Å
(d) None of these

B

Question. In an electron gun, the potential difference between the filament and plate is 3000 V. What will be the velocity of electron emitting from the gun?
(a) 3 × 108 m/s
(b) 3.18 × 107 m/s
(c) 3.52 × 107 m/s
(d) 3.26 × 107 m/s

D

Question. If the X-ray tube is working at 20 kV then the minimum wavelength of X-rays will be
(a) 0.31 Å
(b) 0.62 Å
(c) 0.93 Å
(d) 0.47 Å

B

Question. When X-rays of wavelength 0.5 Å would be transmitted by an aluminium tube of thickness 7 mm, its intensity remains one-fourth. The attenuation coefficient of aluminium for these X-rays is
(a) 0.188 mm–1
(b) 0.189 mm–1
(c) 0.198 mm–1
(d) None of these

C

Question. Which metal will be suitable for a photoelectric cell using light of wavelength 4000Å. The work functions of sodium and copper are respectively 2.0 eV and 4.0 eV.
(a) Sodium
(b) Copper
(c) Both
(d) None of these

A

Question. What is the energy of ka X-ray photon of copper (Z = 29) ?
(a) 7.99 keV
(b) 8.29 keV
(c) 8.25 keV
(d) 7.19 keV

A

Question. The de-Broglie wavelength of a neutron at 927°C is l. What will be its wavelength at 27 °C ?
(a) 2/λ
(b) λ
(c) 2 λ
(d) 4 λ

C

Question. All electrons ejected from a surface by incident light of wavelength 200nm can be stopped before travelling 1m in the direction of uniform electric field of 4N/C. The work function of the surface is
(a) 4 eV
(b) 6.2 eV
(c) 2 eV
(d) 2.2 eV

D

Question. he frequency and work function of an incident photon are v and f0. If v0 is the threshold frequency then necessary condition for the emission of photoelectron is
(a) v < v0
(b) v = v0/2
(c) v ≥ v0
(d) None of these

C

Question. The maximum distance between interatomic lattice planes is 15 Å. The maximum wavelength of X-rays which are diffracted by this crystal will be
(a) 15 Å
(b) 20 Å
(c) 30 Å
(d) 45 Å

C

Question. An X-ray tube is operated at 15 kV. Calculate the upper limit of the speed of the electrons striking the target.
(a) 7.26 × 107 m/s
(b) 7.62 × 107 m/s
(c) 7.62 × 107 cm/s
(d) 7.26 × 109 m/s

A

Question. The work function of aluminium is 4.2 eV. If two photons, each of energy 3.5 eV strike an electron of aluminium, then emission of electrons
(a) will be possible
(b) will not be possible
(c) Data is incomplete
(d) Depends upon the density of the surface

B

Question. The stopping potential (V0) versus frequency (v) plot of a substance is shown in figure, the threshold wavelength is

(a) 5 × 1014m
(b) 6000 Å
(c) 5000 Å
(d) Cannot be estimated from given data

B

Question. A monochromatic source of light operating at 200 W emits 4 × 1020 photons per second. Find the wavelength of light.
(a) 400 mm
(b) 200 nm
(c) 4 × 10–10 Å
(d) None of these

A

Question. A photon of 1.7 × 10–13 joule is absorbed by a material under special circumstances. The correct statement is
(a) Electrons of the atom of absorbed material will go the higher energy states
(b) Electron and positron pair will be created
(c) Only positron will be produced
(d) Photoelectric effect will occur and electron will be produced

B

Question. The glancing angle in a X-ray diffraction is 30º and the wavelength of X-rays used is 20 nm. The interplanar spacing of the crystal dffracting these X-rays will be
(a) 40 nm
(b) 20 nm
(c) 15 nm
(d) 10 nm

B

Question. For intensity I of a light of wavelenght 5000Å the photoelectron saturation current is 0.40 μA and stopping potential is 1.36 V, the work function of metal is
(a) 2.47 eV
(b) 1.36 eV
(c) 1.10 eV
(d) 0.43 eV

C

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 photoelectric emission is nearly
(a) 2 V
(b) 3 V
(c) 5 V
(d) 1 V

A

Question. A source S1 is producing, 1015 photons per second of wavelength 5000 Å. Another source S2 is producing 1.02×1015 photons per second of wavelength 5100Å Then, (power of S2) to the (power of S1) is equal to :
(a) 1.00
(b) 1.02
(c) 1.04
(d) 0.98

A

Question. Light from a hydrogen discharge tube is incident on the cathode of a photoelectric cell, the work function of the cathode surface is 4.2 eV. In order to reduce the photocurrent to zero the voltage of the anode relative to the cathode must be made
(a) – 4.2 V
(b) – 9.4 V
(c) – 17.8 V
(d) + 9.4 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

D

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

D

Question. If the momentum of electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%. The initial momentum of electron will be
(a) 200 P
(b) 400 P
(c) P/100
(d) (100/p)

A

Question. A 200 W sodium street lamp emits yellow light of wavelength 0.6 μm. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
(a) 1.5 × 1020
(b) 6 × 1018
(c) 62 × 1020
(d) 3 × 1019

A

Question. A radio transmitter operates at a freqency 880 kHz and a power of 10 kW. The number of photons emitted per second is
(a) 1.72 × 1031
(b) 1.327 × 1025
(c) 1.327 × 1037
(d) 1.327 × 1045

A

Question. 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 materials is
(a) 4 × 1015 Hz
(b) 5 × 1015 Hz
(c) 1.6 × 1015 Hz
(d) 2.5 × 1015 Hz

C

Question. For a given photosensitive material and frequency (> threshold frequency) of incident radiation, the photoelectric current varies with the intensity of incident light as

A

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) 1.2 V
(c) 0.5 V
(d) 2.3 V

C

Question. The anode voltage of a photocell is kept fixed. The wavelength λ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows

D

Question. Radiations of intensity 0.5 W/m2 are striking a metal plate. The pressure on the plate is
(a) 0.166 × 10–8 N/m2
(b) 0.332 × 10–8 N/m2
(c) 0.111 × 10–8 N/m2
(d) 0.083 × 10–8 N/m2

A

Question. The wavelength of a 1 keV photon is 1.24 × 10–9 m. What is the frequency of 1 MeV photon ?
(a) 1.24 × 1015
(b) 2.4 × 1020
(c) 1.24 × 1018
(d) 2 × 4 × 1023

B

Question. Photoelectric work function of a metal is 1eV. Light of wavelength l = 3000 Å falls on it. The photo electrons come out with velocity
(a) 10 metres/sec
(b) 102 metres/sec
(c) 104 metres/sec
(d) 106 metres/sec

D

Question. The momentum of a photon of an electromagnetic radiation is 3.3 × 10–29 kgms–1. What is the frequency of the associated waves ?
[h = 6.6 × 10–34 Js; c = 3 × 108 ms–1)
(a) 1.5 × 1013 Hz
(b) 7.5 × 1012 Hz
(c) 6.0 × 103 Hz
(d) 3.0 × 103 Hz

A

Question. Hard X-rays for the study of fractures in bones should have a minimum wavelength of 10–11 m. The accelerating voltage for electrons in X-ray machine should be
(a) < 124 kV
(b) > 124 kV
(c) between 60 kV and 70 kV
(d) = 100 kV

A

Question. The wavelength of a photon needed to remove a proton from a nucleus which is bound to the nuclear with 1 MeV energy is nearly
(a) 1.2 nm
(b) 1.2 × 10–3 nm
(c) 1.2 × 10–6 nm
(d) 1.2 × 10 nm

B

Question. The threshold frequency for photoelectric effect on sodium corresponds to a wavelength of 5000 Å. Its work function is
(a) 4 × 10–19 J
(b) 1 J
(c) 2 × 10–19 J
(d) 3 × 10–19 J

A

Question. A particle is dropped from a height H. The de-Broglie wavelength of the particle as a function of height is proportional to
(a) H
(b) H1/2
(c) H0
(d) H–1/2

D

Question. Consider a beam of electrons (each electron with energy E0) incident on a metal surface kept in an evacuated chamber. Then,
(a) no electrons will be emitted as only photons can emit electrons
(b) electrons can be emitted but all with an energy, E0
(c) electrons can be emitted with any energy, with a maximum of E0 – f (f is the work function)
(d) electrons can be emitted with any energy, with a maximum of E0

D

Question. When the energy of the incident radiation is incredased 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. Consider figure given below. Suppose the voltage applied to A is increased. The diffracted beam will have the maximum at value of θ that

(a) will be larger than the earlier value
(b) will be the same as the earlier value
(c) will be less than the earlier value
(d) will depend on the

C

Question. An electron (mass m) with an initial velocity v = v0 ˆi is in an electric field E = E0 ˆj . If λ0 = h /mv, it’s de-Broglie wavelnegth at time t is given by

C

Question. A source of light is placed at a distance of 50 cm from a photocell and the stopping potential is found to be V0. If the distance between the light source and photocell is made 25 cm, the new stopping potential will be
(a) 2V0
(b) V0/2
(c) V0
(d) 4V0

C

Question. 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 :
(a) 25
(b) 75
(c) 60
(d) 50

B

Question. The de-Broglie wavelength of neutron in thermal equilibrium at temperature T is

A

Question. Which of the following figures represents the variation of particle momentum and the associated de-Broglie wavelength?

A

Question. The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (Kelvin) and mass m, is :-

A

Question. Light of wavelength 500 nm is incident on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is
(a) < 2.8 × 10-9 m
(b) > 2.8 × 10-9 m
(c) < 2.8 × 10-12 m
(d) < 2.8 × 10-10 m

B

Question. For photoelectric emission from certain metal the cut-off frequency is n. If radiation of frequency 2V impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)

B

Question. The photoelectric threshold wavelength of silver is 3250 × 10–10m. 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 eVs and c = 3 × 108 ms–1)
(a) ≈ 0.6 × 106 ms–1
(b) ≈ 61 × 103 ms–1
(c) ≈ 0.3 × 106 ms–1
(d) ≈ 6 × 105 ms–1