Dual Nature of Matter & Radiation PYQs Set 1 (PDF)

Back to Dual Nature of Matter & Radiation

Set 1 of 11 · Questions 1-30 of 313

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions NEET Physics · Dual Nature of Matter & Radiation · Set 1 (Q1-30)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
1. $If the wavelength of the first member of Lyman series of hydrogen is λ . The wavelength of the second member will be$ (1) $\frac{27}{32} λ$ (2) $\frac{32}{27} λ$ (3) $\frac{27}{5} λ$ (4) $\frac{5}{27} λ$ 2. $When a metal surface is illuminated by light of wavelength λ, the stopping potential is 8 V . When the same surface is illuminated by light of wavelength 3 λ, stopping potential is 2 V . The threshold wavelength for this surface is:$ (1) $5 λ$ (2) $3 λ$ (3) $9 λ$ (4) $4.5 λ$ 3. $A proton and an electron are associated with same de-Broglie wavelength. The ratio of their kinetic energies is: (Assume h = 6.63 \times 10^{- 34} J s, m_{e} = 9.0 \times 10^{- 31} kg and m_{p} = 1836 times m_{e})$ (1) $1 : 1836$ (2) $1 : \frac{1}{1836}$ (3) $1 : \frac{1}{1836}$ (4) $1 : 1836$ 4. $When light of wavelength 300 nm (nanometer) falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, however, light of 600 nm wavelength is sufficient for creating photoemission. What is the ratio of the work functions of the two emitters?$ (1) $1:2$ (2) $2:1$ (3) $4:1$ (4) $1:4$ 5. $A charged particle is accelerated from rest through a certain potential difference. The de-Broglie wavelength is λ_{1} when it is accelerated through V_{1} and is λ_{2} when accelerated through V_{2} . The ratio λ_{1} / λ_{2} is$ (1) $V_{1}^{3/2} : V_{2}^{3/2}$ (2) $V_{2}^{1/2} : V_{1}^{1/2}$ (3) $V_{1}^{1/2} : V_{2}^{1/2}$ (4) $V_{1}^{2} : V_{2}^{2}$ 6. $An electron of mass m and a photon have same energy E . The ratio of de-Broglie wavelengths associated with them is [NEET 2016]$ (1) $(\frac{E}{2 m})^{1/2}$ (2) $c (2 mE)^{1/2}$ (3) $\frac{1}{c} (\frac{2 m}{E})^{1/2}$ (4) $\frac{1}{c} (\frac{E}{2 m})^{1/2}$ 7. $Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively, successively illuminate a metallic surface whose work function is 0.5 eV . Ratio of maximum speeds of emitted electrons will be$ (1) $1 : 4$ (2) $1 : 1$ (3) $1 : 5$ (4) $1 : 2$ 8. $The maximum kinetic energy of emitted electrons in a photoelectric effect does not depend upon$ (1) $intensity$ (2) $work function$ (3) $wavelength$ (4) $frequency$ 9. $In a photo electric experiment, the wavelength of the light incident on the metal is changed from 200 nm to 400 nm . The decrease in the stopping potential is close to [Use hc = 1240 eV -nm where h = Planck's constant and c is velocity of light].$ (1) $3.1 V$ (2) $2.8 V$ (3) $4.2 V$ (4) $1.2 V$ 10. $In a discharge tube ionization of enclosed gas is produced due to collisions between$ (1) $neutral gas atoms/molecules$ (2) $positive ions and neutral atoms/ molecules$ (3) $negative electrons and neutral atoms/ molecules$ (4) $photons and neutral atoms/molecules.$ 11. $The energy that should be added to an electron to reduce ils de-Broglie wavelength from 1 nm to 0.5 nm is$ (1) $four-limes the Initial energy$ (2) $equal to the initial energy$ (3) $two-times the initial energy$ (4) $three-times the initial energy$ 12. $Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V The threshold frequency of the material is$ (1) $4 \times 1 0^{15} Hz$ (2) $5 \times 1 0^{15} Hz$ (3) $1.6 \times 1 0^{15} Hz$ (4) $2.5 \times 1 0^{15} Hz$ 13. $In a photocell, frequency of incident radiation is increased by keeping other factors constant ((v) > v_{0}), the stopping potential$ (1) $decreases$ (2) $increases$ (3) $becomes zero$ (4) $first decreases and then increases$ 14. $The wavelength of a 1 keV photon is 1.24 \times 1 0^{- 9} m . What is the frequency of 1 MeV photon?$ (1) $1.24 \times 1 0^{15}$ (2) $2.4 \times 1 0^{20}$ (3) $1.24 \times 1 0^{18}$ (4) $2.4 \times 1 0^{23}$ 15. $When UV light of wavelength 300 nm is incident on the metal surface having work function 2.13 eV, electron emission takes place. The stopping potential is: (Given hc = 1240 eVnm)$ (1) $1.5 V$ (2) $4.1 V$ (3) $2 V$ (4) $4 V$ 16. $On a photosensitive material, when frequency of incident radiation is increased by 30 %, kinetic energy of emitted photoelectrons increases from 0.4 eV to 0.9 eV . The work function of the surface is$ (1) $1 eV$ (2) $1.267 eV$ (3) $1.4 eV$ (4) $1.8 eV$ 17. $Monochromatic radiation is incident on hydrogen (H) sample which is in ground state. If the hydrogen atoms emit radiation of ten different wavelengths after absorbing the incident radiation, then the wavelength of the incident radiation is (Let hc = 1242 eV - nm)$ (1) $84.4 nm$ (2) $102.6 nm$ (3) $72.5 nm$ (4) $95.1 nm$ 18. $A light wave described by E = 60 (sin (3 \times 10^{15}) t + sin (12 \times 10^{15}) t) (in SI units) falls on a metal surface of work function 2.8 eV . The maximum kinetic energy of ejected photoelectron is (approximately)____eV. (h = 6.6 \times 10^{- 34} J . s. and e = 1.6 \times 10^{- 19} C)$ (1) $7.8$ (2) $6.0$ (3) $5.1$ (4) $3.8$ 19. $In photoelectric experiment, if both the intensity and frequency of the incident light are doubled, then the saturation photoelectric current$ (1) $is doubled$ (2) $remains constant$ (3) $becomes for times$ (4) $is halved$ 20. $Hydrogen atom is in its n^{th} energy state. If de-Broglie wavelength of the electron is λ,then$ (1) $λ \propto \frac{1}{n ^{2}}$ (2) $λ \propto \frac{1}{n}$ (3) $λ \propto n^{2}$ (4) $λ \propto n$ 21. $A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and λ /2 . If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is (h = Planck's constant, c = speed of light)$ (1) $\frac{hc}{2 λ}$ (2) $\frac{hc}{λ}$ (3) $\frac{2 hc}{λ}$ (4) $\frac{hc}{3 λ}$ 22. $A light source of wavelength λ illuminates a metal surface and electrons are ejected with maximum kinetic energy of 2 eV. If the same surface is illuminated by a light source of wavelength \frac{λ}{2}, then the maximum kinetic energy of ejected electrons will be (The work function of metal is 1 eV)$ (1) $3 ev$ (2) $2 eV$ (3) $6 eV$ (4) $5 eV$ 23. $The de Brogue wavelengths for an electron and a photon are λ_{e} and λ_{p} respectively. For the same kinetic energy of electron and photon, which of the following presents the correct relation between the de Brogue wavelengths of two?$ (1) $λ_{p} \propto λ_{e}^{2}$ (2) $λ_{p} \propto λ_{e}$ (3) $λ_{p} \propto λ_{e}$ (4) $λ_{p} \propto \frac{1}{λ _{e}}$ 24. $The de-Broglie wavelength (λ) of a particle is related to its kinetic energy (E) as$ (1) $λ \propto E$ (2) $λ \propto E^{- 1}$ (3) $λ \propto E^{1/2}$ (4) $λ \propto E^{- 1/2}$ 25. $The de Broglie wavelength of an electron accelerated between two plates having a potential difference of 900 V is nearly$ (1) $0.015 nm$ (2) $0.01 nm$ (3) $0.02 nm$ (4) $0.04 nm$ 26. $If the momentum of an electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%. The initial momentum of electron will be$ (1) $200 P$ (2) $400 P$ (3) $P /200$ (4) $100 P$ 27. $The number of photons per second on average emitted by the source of monochromatic light of wavelength 600 nm , when it delivers the power of 3.3 \times 10^{- 3} W will be (h = 6.6 \times 10^{- 34} J - s) [NEET 2021]$ (1) $10^{18}$ (2) $10^{17}$ (3) $10^{16}$ (4) $10^{15}$ 28. $Maximum velocity of the photoelectrons emitted by a metal surface 1.2 \times 10^{6} m s^{- 1} . Assuming the specific charge of the electron to be 1.8 \times 10^{11} C kg^{- 1}, the value of the stopping potential in volt will be$ (1) $2$ (2) $3$ (3) $4$ (4) $6$ 29. $The magnetic field of a plane electromagnetic wave is B \to= 3 \times 10^{- 8} sin [200 π (y + ct)] i^T where c = 3 \times 10^{8} ms^{- 1} is the speed of light. The corresponding electric field is$ (1) $E \to= - 9 sin [200 π (y + ct)] k^V / m$ (2) $E \to= 9 sin [200 π (y + ct)] k^V / m$ (3) $E \to= - 10^{- 6} sin [200 π (y + ct)] k^V / m$ (4) $E \to= 3 \times 10^{- 8} sin [200 π (y + ct)] k^V / m$ 30. $An electron of mass m and a photon have same energy E . The ratio of de‐Broglie wavelengths associated with them is (c being velocity of light)$ (1) $c (2 mE)^{\frac{1}{2}}$ (2) $\frac{1}{c} (\frac{2 m}{E})^{\frac{1}{2}}$ (3) $\frac{1}{c} (\frac{E}{2 m})^{\frac{1}{2}}$ (4) $(\frac{E}{2 m})^{\frac{1}{2}}$