Dual Nature Of Radiation And Matter Mock Test

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Quiz: Dual Nature of Radiation and Matter – Progressive Test
Total questions: 380
Questions in this round: 50
Time allotted: 70 minutes
Pass score: 60%
Total rounds: 8
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Quiz: Dual Nature of Radiation and Matter – Certificate Challenge
Total questions: 380
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1 / 50

1. Consider the following statements about basic quantities used in dual nature.
Statement I: is Planck’s constant.
Statement II: is the speed of light in vacuum.
Statement III: is measured in .

a) I, II and III

b) I and III only

c) II and III only

d) I and II only

2 / 50

2. The stopping potential in a photoelectric experiment is the magnitude of the retarding potential that

a) makes the collector attract all emitted photoelectrons

b) doubles the work function of the emitting metal

c) stops even the fastest photoelectrons

d) changes the frequency of incident radiation to threshold frequency

3 / 50

3. 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.

a) I and III only

b) II and III only

c) I, II and III

d) I and II only

4 / 50

4. Consider the following statements about the basic photoelectric effect.
Statement I: It is the emission of electrons from a metal surface due to suitable radiation.
Statement II: It can occur even when the incident frequency is below the threshold frequency, provided the intensity is high enough.
Statement III: The emitted electrons are called photoelectrons.

a) I and II only

b) I, II and III

c) II and III only

d) I and III only

5 / 50

5. The graph description below is used.

For accelerated electrons, a plot of scattered intensity against angle shows a pronounced maximum. When the accelerating voltage is changed, the position of the maximum changes.

The most suitable reason for the shift of the maximum is that changing the voltage changes

a) Planck’s constant

b) the electron de Broglie wavelength

c) the metal work function of the detector

d) the electron charge

6 / 50

6. A light beam of fixed intensity falls on the same photoelectric surface. Beam has photon energy , and beam has photon energy . Both are above threshold. If the emission probability per incident photon is the same, the saturation current for compared with is expected to be

a) four times as large

b) equal

c) twice as large

d) half as large

7 / 50

7. A classical wave-based claim says, “Increasing intensity should increase the maximum kinetic energy of photoelectrons.” The observed photoelectric result contradicts this because

a) depends on incident frequency, not intensity

b) frequency affects only the number of emitted electrons

c) intensity has no effect on photoelectric current

d) increases with intensity only below threshold

8 / 50

8. Two photons have wavelengths and . The momentum of the photon is

a) twice the momentum of the photon

b) equal to the momentum of the photon

c) half the momentum of the photon

d) four times the momentum of the photon

9 / 50

9. Two non-relativistic electrons are accelerated from rest through and . The ratio of their de Broglie wavelengths is

10 / 50

10. After acceleration from rest through potential difference , an electron gains kinetic energy

11 / 50

11. A radiation of wavelength falls on a metal of threshold wavelength . The correct conclusion is that

a) photoemission is impossible at every wavelength shorter than threshold

b) photoemission occurs only if intensity is zero

c) photoemission occurs because

d) photoemission does not occur because

12 / 50

12. For radiation of fixed frequency , increasing the intensity mainly means that

a) each photon has larger energy

b) more photons arrive per unit time

c) the work function of the metal decreases

d) the speed of light in vacuum increases

13 / 50

13. A photoelectron has maximum kinetic energy . The stopping potential needed to stop it is

14 / 50

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

15 / 50

15. A monochromatic beam of intensity falls normally on an area . Each photon has energy . Using , the photon arrival rate on the area is

16 / 50

16. An electron and a proton have the same speed , while another electron has speed . Which arrangement of de Broglie wavelengths is correct?

b) all three wavelengths are equal because all are particles

17 / 50

17. Two metals have threshold wavelengths and . The metal with threshold wavelength has

a) half the work function of the metal

b) twice the work function of the metal

c) four times the work function of the metal

d) the same work function as the metal

18 / 50

18. Assertion: Photoelectric emission starts nearly instantaneously when suitable radiation falls on a metal surface.
Reason: In the photon picture, a single photon can transfer its energy as a whole to one electron.

a) Both Assertion and Reason are true, and Reason explains Assertion

b) Both Assertion and Reason are true, but Reason does not explain Assertion

c) Assertion is false, but Reason is true

d) Assertion is true, but Reason is false

19 / 50

19. Classical wave theory failed to explain the existence of threshold frequency because it suggested that

a) photons have energy

b) no electron can ever absorb energy from light

c) any frequency could emit if made intense enough

d) wavelength and frequency are unrelated for light

20 / 50

20. A beam of electrons accelerated through is used in Davisson-Germer type scattering. The electron wavelength is of the order of , which is significant because it is

a) exactly equal to zero

b) independent of the accelerating voltage

c) larger than the size of Earth

d) comparable with crystal atomic spacing

21 / 50

21. A threshold-relation record is shown below.

Row	Quantity	Relation for the same metal
P	Work function and threshold frequency
Q	Work function and threshold wavelength
R	Threshold frequency and threshold wavelength
S	Threshold wavelength and work function

The mismatched row is

a) Q

b) P

c) R

d) S

22 / 50

22. A photoelectric calculation gives after substituting values into . The correct physical interpretation is

a) the stopping potential is as a measured magnitude

b) the metal work function has become negative

c) the emitted photoelectron moves opposite to the incident light

d) no emission because photon energy is below

23 / 50

23. From a surface whose threshold wavelength is , a beam produces photoelectrons. If the wavelength is changed to with the same metal, the maximum kinetic energy

a) becomes negative and the electrons move backward

b) becomes zero because

c) decreases but remains non-zero

d) increases because wavelength becomes closer to

24 / 50

24. The work function of a metal is . Radiation with photon energy , , and is tried one by one. Which outcome is expected?

a) Emission occurs only for

b) Emission occurs for all three photon energies

c) Emission occurs only for

d) Emission occurs for and

25 / 50

25. Under above-threshold illumination, a photoelectric tube gives at a high positive collector potential, and no further increase is observed when the potential is raised. The number of photoelectrons emitted per second is approximately

26 / 50

26. A photon and an electron are assigned the same wavelength . Which comparison is correct?

a) They have the same rest mass because their wavelengths are the same

b) They must have the same kinetic energy

c) same momentum magnitude, different energy relations

d) They must travel with the same speed in vacuum

27 / 50

27. Threshold-frequency comparison uses radiations of frequencies , , and incident separately on a metal whose threshold frequency is . The case with the largest maximum kinetic energy is

d) all three give the same

28 / 50

28. A claim says, “Since a photon has zero rest mass, it cannot have momentum.” The best correction is that a photon

a) has no energy if its rest mass is zero

b) has mass equal to electron mass whenever it enters a metal

c) has zero rest mass but nonzero momentum

d) has momentum only when it is at rest

29 / 50

29. Assertion: For fixed frequency above threshold, increasing intensity can increase photoelectric current without increasing stopping potential.
Reason: Increasing intensity at fixed frequency increases photon number rate, while the energy of each photon remains .

a) Assertion is false, but Reason is true

b) Assertion is true, but Reason is false

c) Both Assertion and Reason are true, and Reason explains Assertion

d) Both Assertion and Reason are true, but Reason does not explain Assertion

30 / 50

30. A photoelectric-current table is shown below.

Change made	Expected graph change
P. Increase intensity at fixed	Saturation current increases
Q. Increase frequency at adjusted intensity	Stopping potential increases
R. Make collector more negative	Current decreases in the retarding region
S. Increase positive collector potential after saturation	Current keeps increasing linearly without limit

The mismatched row is

a) S

b) R

c) P

d) Q

31 / 50

31. At saturation, a photoelectric tube gives current . Estimate the number of photoelectrons collected per second. Take .

32 / 50

32. For work function , radiation of wavelength falls on a metal. Using , the stopping potential is closest to

33 / 50

33. Under above-threshold monochromatic illumination, a detector shows lower saturation current when frequency is increased while beam intensity is fixed. A suitable reason is that

a) higher frequency necessarily lowers photon energy

b) the photon number rate may decrease at fixed intensity

c) the work function becomes negative at high frequency

d) stopping potential becomes independent of frequency

34 / 50

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

a) the radiation has no photon energy

b) metal may have too large a work function

c) both metals must have identical threshold frequencies

d) metal has a higher work function than metal

35 / 50

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

Frequency

The value of obtained from the graph is

36 / 50

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

37 / 50

37. A fixed-power light source illuminates a photoelectric surface. When the photon energy is changed from to , the work function remains , and the emission probability per photon remains the same. The correct comparison is

a) saturation current halves and rises from to

b) saturation current becomes zero for the photons

c) saturation current doubles and stopping potential halves

d) saturation current remains unchanged and stopping potential remains unchanged

38 / 50

38. Consider the following statements about matter waves and uncertainty.
Statement I: Wave-particle duality suggests that microscopic particles cannot always be described by exact classical paths.
Statement II: Matter waves require a material medium like sound waves.
Statement III: A highly localized matter wave is associated with a spread in momentum values.

a) I and III only

b) II and III only

c) I and II only

d) I, II and III

39 / 50

39. Read the comparison below.

Radiation has very high intensity but frequency below . Radiation has low intensity but frequency above . The metal surface is clean and the observations are made under normal photoelectric conditions.

What is the expected photoelectric response?

a) neither emits because low intensity prevents all emission

b) emits none, while can emit a small current

c) both emit the same current because intensity is irrelevant

d) emits many electrons, while emits none

40 / 50

40. A data table for two above-threshold beams falling on the same metal area is shown below.

Beam	Intensity	Photon energy	Photon rate trend
P
Q
R

The missing photon rates for and are respectively

a) and

b) and

c) and

d) and

41 / 50

41. In a straight-line graph of versus for a metal, the slope is . Taking , the value of obtained from the graph is closest to

42 / 50

42. From a straight-line photoelectric graph of versus , the line passes through and . The work function of the metal in is

43 / 50

43. At threshold frequency , Einstein’s equation reduces to

b) with

c) with

44 / 50

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

45 / 50

45. If the collector in Lenard’s experiment is made positive with respect to the emitter, the immediate effect on emitted photoelectrons is that they are

a) attracted toward the collector

b) stopped at the emitter surface in every case

c) converted into neutral atoms

d) forced to become photons

46 / 50

46. The quantum idea of radiation says that electromagnetic radiation exchanges energy with matter in

a) packets called photons

b) particles with ordinary rest mass equal to electron mass

c) mechanical pulses that need air

d) continuous amounts of any possible size only

47 / 50

47. Two beams are compared. Beam P consists of photons of wavelength . Beam Q consists of electrons with de Broglie wavelength . Which statement avoids a formula-choice error?

a) Use for photons and electrons equally

b) Use for both beams as their kinetic energy

c) Use for both beams without a metal surface

d) photon formula for photons; de Broglie formula for electrons

48 / 50

48. For , radiation of photon energy is incident on a metal. The stopping potential corresponding to the fastest photoelectrons is

49 / 50

49. Two photoelectric - curves for the same metal reach the same saturation current, but curve cuts the negative potential axis farther from the origin than curve . This most likely means that curve was obtained with

a) below-threshold radiation of greater intensity

b) greater intensity at the same frequency

c) lower frequency and greater work function

d) higher frequency with adjusted intensity

50 / 50

50. In a Davisson-Germer type intensity graph, scattered electron intensity is plotted against scattering angle. A sharp peak at a certain angle means

a) the electrons have become photons with visible wavelength

b) the electrons have lost all kinetic energy before reaching the crystal

c) the nickel crystal has stopped acting like a periodic structure

d) constructive interference of electron matter waves from crystal planes

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

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