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
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Quiz: Dual Nature of Radiation and Matter – Certificate Challenge
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1 / 50

1. When the photoelectric current becomes zero at a certain negative collector potential, this zero-current condition means that

a) all emitted electrons have zero charge

b) the collector has reached saturation current

c) the incident light has become monochromatic

d) fastest electrons miss the collector

2 / 50

2. Consider the following statements about photoelectric graph interpretation.
Statement I: The negative intercept of an - curve gives the stopping potential magnitude.
Statement II: The plateau current of an - curve gives information about the emitted-electron rate.
Statement III: The slope of the - curve in the saturation region gives Planck’s constant.

a) I and II only

b) I, II and III

c) I and III only

d) II and III only

3 / 50

3. 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) stopped at the emitter surface in every case

b) attracted toward the collector

c) forced to become photons

d) converted into neutral atoms

4 / 50

4. A proton and an electron have the same de Broglie wavelength. Their momenta must be

a) inversely proportional to their charges

b) zero for both particles

c) in the ratio of their masses

d) equal in magnitude

5 / 50

5. The relation between photon energy and photon momentum is

6 / 50

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

a) A metal surface becoming positively charged after losing electrons

b) Electron diffraction by a crystal

c) Heating a metal wire until electrons are emitted

d) A photon carrying energy proportional to its frequency

7 / 50

7. 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 and III only

b) I, II and III

c) I and II only

d) II and III only

8 / 50

8. A moving particle has de Broglie wavelength . If another particle has the same Planck constant context but twice the momentum, its de Broglie wavelength is

9 / 50

9. The straight-line equation for stopping potential as a function of frequency is

10 / 50

10. A record of four surface-emission cases is shown below.

Case	Observation	Named process
P	Electron emission after heating a metal filament	Thermionic emission
Q	Electron emission after ultraviolet light falls on zinc	Photoelectric emission
R	Electron emission due to a strong surface electric field	Secondary emission
S	Electron emission after fast particles hit a surface	Secondary emission

Which case contains the mismatched named process?

a) Case Q

b) Case R

c) Case P

d) Case S

11 / 50

11. A non-relativistic particle has mass and kinetic energy . If its kinetic energy becomes , its de Broglie wavelength becomes

12 / 50

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

13 / 50

13. Read the observation and answer the question.

A freshly cleaned metal surface is placed in an evacuated chamber. Radiation is allowed to fall on the surface. For one colour no electron emission is observed even at high intensity. For another colour electron emission begins immediately and a small current is recorded when a collector is connected.

What conclusion is most consistent with the observation?

a) The recorded current is due to neutral atoms leaving the metal

b) High intensity always prevents photoelectric emission

c) The second colour must have zero frequency

d) The first colour is below threshold frequency

14 / 50

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

15 / 50

15. A crystal has plane spacing . An electron beam of wavelength gives first-order constructive scattering. The Bragg angle is

16 / 50

16. With threshold frequency and , the stopping potential at is

17 / 50

17. If incident radiation produces photoelectrons with stopping potential from a metal of work function , the incident photon energy and threshold-frequency relation are

a) and

b) and

c) and

d) and

18 / 50

18. Two metals have - lines with the same slope. The threshold frequency of metal is greater than that of metal by . If , the work function of exceeds that of by

19 / 50

19. A summary table of photoelectric laws is shown below.

Row	Condition changed	Observed effect
P	Intensity increased at fixed	Photoelectric current increases
Q	Frequency increased for same metal	increases
R	Frequency below	No emission, even at high intensity
S	Intensity increased at fixed frequency	Stopping potential necessarily increases

The row that does not follow the experimental laws is

a) P

b) R

c) Q

d) S

20 / 50

20. A neutron has kinetic energy . Since it is neutral, it cannot be accelerated through a potential difference in the same direct way as an electron. Its de Broglie wavelength is still given by

21 / 50

21. For threshold frequency , radiation of frequency is used. If , the stopping potential is

22 / 50

22. Energetic electrons strike a metal target and cause other electrons to leave the target surface. The emission from the target is called

a) thermionic emission

b) photoelectric emission

c) field emission

d) secondary emission

23 / 50

23. A prediction-observation table is given below.

Feature	Classical wave expectation	Experimental observation
P	No sharp threshold frequency	Definite threshold frequency exists
Q	Higher intensity should raise	depends on frequency
R	Low intensity may cause time delay	Emission is nearly instantaneous

The table is best used to show

a) the need for the photon picture

b) that intensity has no effect on any photoelectric quantity

c) why the classical wave theory succeeds completely

d) that threshold frequency is the same for all metals

24 / 50

24. The relation shows that photon energy is

a) inversely proportional to

b) equal to wavelength for all photons

c) directly proportional to wavelength

d) independent of wavelength

25 / 50

25. A comparison of frequency effects is shown below.

Change made for the same metal	Effect on	Effect on
P. Frequency increased above	Increases	Increases
Q. Frequency reduced to exactly	Becomes	Becomes
R. Frequency reduced below	No photoemission	No stopping potential measured

The assessment of the table is

a) P, Q and R are valid

b) only P and Q are valid

c) only P is valid

d) only Q and R are valid

26 / 50

26. A radiation packet has energy . Express this energy in , using .

27 / 50

27. Einstein’s photoelectric equation is written as

28 / 50

28. Photon momentum for radiation of wavelength is given by

29 / 50

29. The same photoelectric surface is illuminated first by radiation of frequency and then by radiation of frequency . If , the increase in stopping potential is closest to

30 / 50

30. For a non-relativistic particle of mass moving with speed , the de Broglie wavelength is

31 / 50

31. When a photon falls on a metal surface of work function , the photoelectric response is

a) emission with

b) no emission because photon energy is below

c) emission with

d) emission only if the stopping potential is negative

32 / 50

32. A claim about the - graph says, “The vertical intercept is positive because stopping potential is always positive.” The best response is that

a) the vertical intercept is for all metals

b) the graph has no intercept because it is a circle

c) the vertical intercept is

d) the vertical intercept gives saturation current, so its sign is meaningless

33 / 50

33. Photoelectrons in a retarding-potential arrangement have kinetic energies up to . A retarding potential of magnitude is applied. What is the expected result?

a) Only photoelectrons with are stopped

b) No photoelectron is affected by the retarding potential

c) The work function becomes

d) All photoelectrons are stopped

34 / 50

34. For a photon of wavelength , taking , its momentum is approximately

35 / 50

35. A straight - line for metal is shifted to the right compared with another metal, while both lines remain parallel. The rightward shift means metal has

a) no photoelectric threshold

b) a larger threshold frequency and larger work function

c) a larger value of Planck’s constant

d) a smaller threshold frequency and smaller work function

36 / 50

36. Consider the following statements about the experimental laws of photoelectric emission.
Statement I: For , photoelectric current increases with intensity.
Statement II: Maximum kinetic energy depends on frequency and not on intensity.
Statement III: Photoelectric emission has a long unavoidable time lag at very low intensity.

a) I and II only

b) I and III only

c) II and III only

d) I, II and III

37 / 50

37. Two intensities are used in a photoelectric experiment with the same frequency above threshold. Intensity is three times . If the saturation current for is , the saturation current for is expected to be

38 / 50

38. For a metal with threshold frequency , the work function is

39 / 50

39. For a metal of work function , radiation of wavelength has photon energy . What maximum kinetic energy can the fastest photoelectrons have?

40 / 50

40. In a crystal diffraction experiment, the first-order maximum for electrons occurs when . If the accelerating voltage is increased, the value of decreases, so the new Bragg angle generally

a) remains unchanged for all voltages

b) decreases for same planes and order

c) increases to always

d) becomes unrelated to crystal spacing

41 / 50

41. An electron needs to just escape from a metal surface. Express this minimum escape energy in . Use .

42 / 50

42. 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) R

b) S

c) P

d) Q

43 / 50

43. 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.

a) I and III only

b) II and III only

c) I and II only

d) I, II and III

44 / 50

44. In the photoelectric effect, the statement “one photon interacts with one electron” means that

a) every electron in the metal must absorb one photon at the same instant

b) a photon shares its energy equally among all electrons in the metal

c) one electron absorbs one photon as a whole

d) one photon first becomes many low-energy photons before emission

45 / 50

45. In the Hertz observation related to photoelectric emission, ultraviolet radiation helped a spark occur more easily between metal electrodes. A suitable interpretation is that ultraviolet radiation

a) reduced the frequency of all incident light to zero

b) helps emit electrons that assist the spark discharge

c) made the electric field vanish between the electrodes

d) changed the metal electrodes into insulators

46 / 50

46. Blue light causes photoemission from a metal, but red light does not. A possible threshold wavelength for the metal is one that lies

a) shorter than blue light wavelength only

b) at zero wavelength

c) longer than all red light wavelengths only

d) between the red and blue wavelengths

47 / 50

47. Two metals give straight - graphs. The two lines are parallel, but the line for metal cuts the frequency axis at a larger frequency than metal . The correct conclusion is that

a) metal has a larger work function than metal

b) both metals must have zero work function

c) metal has a smaller work function than metal

d) the slope for metal is larger than the slope for metal

48 / 50

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

a) voltage-wavelength product and rest-energy relation

b) photon momentum relation and threshold condition

c) electron de Broglie relation and Bragg condition

d) photon energy relation and current relation

49 / 50

49. For fixed incident frequency above , the saturation current in a photoelectric experiment is doubled. A likely cause is that

a) the work function of the metal has doubled

b) the threshold frequency has become half

c) the incident radiation intensity has doubled

d) the collector has been made strongly negative

50 / 50

50. A claim says, “Davisson-Germer experiment proves that electrons are waves and not particles.” A more accurate conclusion is that electrons

a) have no momentum when they form diffraction maxima

b) become electromagnetic waves after acceleration

c) lose all particle properties in every experiment

d) show diffraction but are detected as particles

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

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