Dual Nature of Radiation and Matter Mock Test – Class 12 Physics

1. Consider the following statements about types of electron emission.
Statement I: Photoelectric emission is caused by suitable radiation.
Statement II: Thermionic emission is caused by heating.
Statement III: Field emission is caused by energetic particle impact.

2. For a metal, the stopping potential is at frequency and at frequency . The slope of the - graph is

3. A compact data set for a metal is given below.

The table is best explained by the relation

4. For photon energy , taking , the momentum is closest to

5. Use the arrangement described below.

In this arrangement, plate is mainly used to

6. A photoelectric-current table is shown below.

The mismatched row is

7. Match the electron-emission type with its immediate physical cause.

The correct matching is

8. For first-order constructive electron diffraction from crystal planes of spacing , the Bragg condition is

9. As the collector in a photoelectric tube is gradually made more positive with respect to the emitter while the incident light is kept unchanged, the photoelectric current first increases because

10. The evacuated tube in Lenard’s photoelectric experiment is used mainly to

11. A proton and an alpha particle are accelerated from rest through the same potential difference . Take the alpha particle to have charge and mass approximately . The ratio is

12. Matter-wave behaviour is usually noticed for microscopic particles rather than ordinary large bodies because

13. In electron diffraction, clear diffraction maxima are expected when the electron de Broglie wavelength is

14. A detector in an electron-diffraction experiment records intensity peaks instead of a uniform spread. The peaks show that the electron beam

15. In a light-operated counting system using a photoelectric cell, blocking the incident light beam causes a change in current because

16. A statement says, “In the photoelectric equation, the work function is the energy left after the electron comes out.” The better interpretation is that the work function is

17. An experimental - line has slope . If the accepted value of is close to , the graph mainly confirms that

18. Before striking a nickel crystal in a Davisson-Germer type experiment, electrons are accelerated mainly to

19. A light sensor based on a photoelectric cell mainly works because incident light can

20. For an electron accelerated from rest through potential difference , the non-relativistic de Broglie wavelength is proportional to

21. A stopping-potential graph for a metal passes through and . Taking , the work function and threshold wavelength are respectively

22. At fixed incident intensity and fixed illuminated area, a metal is illuminated first with photons of energy and then with photons of energy . If both photon energies are above the work function, the photon rate in the second case is

23. With work function and incident photon energy , Einstein’s photoelectric equation gives as

24. A row in a graph summary says that the - graph for all metals has the same energy-axis intercept. This row is flawed because

25. The de Broglie hypothesis states that a moving material particle is associated with

26. A claim says, “Increasing the frequency of light always increases photoelectric current.” A better statement is that increasing frequency above threshold certainly tends to increase

27. A photoelectric current versus collector potential graph is described as follows: for increasing positive collector potential, the current rises at first and then becomes nearly constant. The nearly constant part represents

28. Which observation is the clearest evidence for the wave nature of matter?

29. An electron microscope uses electrons accelerated through a high potential difference. If the accelerating voltage is increased, the resolving ability can improve because

30. For two beams of the same frequency above threshold but different intensities, the photoelectric current-potential curves are compared. The expected difference is

31. A data set for one metal is shown below.

The value of obtained from the graph is

32. A student wants to analyse electrons accelerated through a potential and then diffracted by a crystal. The most suitable pair of relations is

33. A student says, “The photoelectric effect and Davisson-Germer experiment are both explained by the same formula .” The best correction is that

34. A unit check for the de Broglie relation should give

35. A comparison of frequency effects is shown below.

The assessment of the table is

36. An electron microscope can resolve much smaller details than an ordinary optical microscope mainly because accelerated electrons can have

37. A claim says, “The uncertainty principle is important only because instruments are poor.” The better statement is that the uncertainty is

38. Two particles have the same kinetic energy , but particle has mass and particle has mass . Their non-relativistic de Broglie wavelengths satisfy

39. For a metal of work function illuminated by light, use . The stopping potential is closest to

40. Davisson and Germer’s experiment is important because it showed

41. For fixed frequency , a graph is plotted between photoelectric current and intensity of incident light.

The graph is linear mainly because

42. Below-threshold radiation is directed at a metal surface. If only the intensity is made extremely large, the expected photoelectric current is

43. The same radiation is incident on two clean metal surfaces. Metal emits photoelectrons, but metal does not. A reasonable conclusion is that

44. For a fixed light frequency above threshold, increasing the positive collector potential beyond the saturation region does not increase the photoelectric current appreciably. This is because

45. Light of wavelength ejects photoelectrons whose maximum speed is . Using , , and , the work function is closest to

46. Consider the following statements about electron emission from metals.
Statement I: Electrons in a metal require external energy or assistance to escape from the surface.
Statement II: Heating and suitable radiation can both cause electron emission.
Statement III: Every free electron inside a metal automatically escapes into vacuum.

47. In Lenard’s apparatus, monochromatic light is used so that

48. The vertical intercept of a - graph, if the straight line is extended to , is

49. An electron beam has de Broglie wavelength . Using , the accelerating potential is closest to

50. A clean metal surface emits electrons when it is strongly heated. The most suitable description is