Dual Nature of Radiation & Matter: Class 12 Previous Year Questions

Dual Nature of Radiation & Matter questions asked in CBSE board exams

Repeated questions first. Open the free app to see each question as it appeared in the paper, with its marking scheme.

1. Find ratio (a/p) of the de Broglie wavelength a and p associated respectively with an alpha particle and a proton, 2 (i) if they are moving with the same kinetic energy. (ii) just after they are accelerated through the same potential difference.
   Board 20262 marksshort answerRepeated: 2022,2026
2. Find the ratio of the de Broglie wavelengths associated with an alpha particle and a proton, if both (a) have the same speeds, (b) have the same kinetic energy, (c) are accelerated through the same potential difference.
   Board 20221 markMCQRepeated: 2022,2026
3. The maximum kinetic energy of the electrons emitted from a photo sensitive surface depends on 1 (A) work function of the surface ‘0’ only. (B) frequency of the incident radiation ‘v’ only. (C) intensity of the incident radiation ‘I’ only. (D) Both 0 and v.
   Board 20261 markMCQ
4.  (D) Assertion (A) is false and Reason (R) is also false. 13. Assertion (A) : On increasing the intensity of incident light of frequency v(> v0) on a photosensitive surface, the photocurrent increases. 1 Reason (R) : The stopping potential for a photosensitiv…
   Board 20261 markAssertion-Reason
5.  30. A researcher performs an experiment on photo-electric effect using two metals A and B with unknown work functions. She illuminates the surfaces of A and B with monochromatic radiation of various frequencies and records the value of corrosponding stopping…
   Board 20264 marksshort answer
6. SECTION - B 17. In a photoelectric experiment, the emitter plate is irradiated with radiation of 200 nm. The photocurrent becomes zero when the collector plate potential is – 0.80 V. Calculate the work function (in eV) of the emitter.
   Board 20262 marksshort answer
7. A light of wavelength 400 nm is incident on metal surface whose work function is 3.0 × 10-19 J. Calculate the speed of the fastest photoelectrons emitted.
   Board 20252 marksshort answer
8. Answer the following giving reason : 26. (a) Ail the photo electrons do not eject with the same kinetic energy when monochromatic light is incident on a metal surface. (b) The saturation current in case (a) is different for different intensity. (c) If one goes…
   Board 20253 marksshort answer
9. When a photon of suitable frequency is incident on a metal surface, photoelectron is emitted from it. If the frequency is below a threshold frequency (v) for the surface, no photoelectron is emitted. For a photon of frequency v(v > v.), the kinetic energy of t…
   Board 20254 marksshort answer
10. The stopping potential Vo measured in a photoelectric experiment for a metal surface is plotted against frequency v of the incident radiation. Let m be the slope of the straight line so obtained. Then the value of charge of an electron is given by (h is the Pl…
    Board 20251 markMCQ
11. Assertion (A) : In photoelectric effect, the kinetic energy of the emitted photoelectrons increases with increase in the intensity of the incident light. Reason (R) : Photoelectric current depends on the wavelength of the incident light.
    Board 20241 markAssertion-Reason
12. Assertion (A) : Photoelectric current increases with an increase in intensity of incident radiation, for a given frequency of incident radiation and the accelerating potential. Reason (R) : Increase in the intensity of incident radiation results in an increase…
    Board 20241 markAssertion-Reason
13. Two beams, A and B whose photon energies are 3·3 eV and 11·3 eV respectively, illuminate a metallic surface (work function 2·3 eV) successively. The ratio of maximum speed of electrons emitted due to beam A to that due to beam B is : (A) 3 (B) 9 (C) 3 1 (D) 9 …
    Board 20241 markMCQ
14. The work function for a photosensitive surface is 3·315 eV. The cut-off wavelength for photoemission of electrons from this surface is : (A) 150 nm (B) 200 nm (C) 375 nm (D) 500 nm 8 9. {H$gr na_mUw Ho$ D$Om© ñVa A, B Am¡a C hþE _mZm| AWm©V² EA < EB < EC Ho$ V…
    Board 20241 markMCQ
15. (a) Figure shows the variation of photoelectric current measured in a photo cell circuit as a function of the potential difference between the plates of the photo cell when light beams A, B, C and D of different wavelengths are incident on the photo cell. Exam…
    Board 20234 marksshort answer
16. (a) Draw the graph showing the variation of the number (N) of scattered alpha particles with scattering angle (0) in Geiger - Marsden experiment. Infer two conclusions from the graph. OR (b) Plot suitable graphs to show the variation of photoelectric current w…
    Board 20221 markvery short
17. (a) (i) nce of closest -particle in Geiger-Marsden scattering experiment. (ii) What will be the value of the impact parameter for scattering angle (I) = 0 and (II) = 180 ? 2 OR (b) Photoelectric emission occurs when a surface is irradiated with the radiation o…
    Board 20221 markvery short
18. The graph below shows the variation of the maximum kinetic energy of the emitted photoelectron with the frequency of the incident radiation for a given metal. Which of the following gives the work function of the metal? A. x-intercept B. y-intercept C. the slo…
    CBSE practice 2023-241 markMCQ
19. g y , gy Q16. Assertion: The kinetic energy of photoelectrons emitted by a photosensitive surface depends upon the frequency of incident photon. Reason: The ejection of electrons from metallic surface is possible with frequency of incident photon below the thr…
    CBSE practice 2023-241 markAssertion-Reason
20. Assertion (A): The work function of a given material increases with an increase in the frequency of the incident radiation. 1 Reason (R): As per Einstein's photoelectric equation hν = φ + KE, work function φ is directly proportional to the frequency ν of the i…
    CBSE practice 2023-241 markAssertion-Reason

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