Photoelectric effect and Einstein’s equation - Question Bank

1. What is the value of the intercept on the frequency axis when E_k is plotted against f in the photoelectric effect?
A) Threshold frequency
B) Work function
C) Planck's constant
D) Zero
2. The work function of a metal is 2.2 eV. If light of wavelength 500 nm is incident on it, what is the maximum kinetic energy of the emitted photoelectrons?
A) 0.28 eV
B) 2.48 eV
C) 2.2 eV
D) 0 eV
3. The photoelectric effect demonstrates that light can behave as:
A) A wave only
B) A particle only
C) Both a wave and a particle
D) Neither a wave nor a particle
4. If the frequency of incident radiation is doubled, the stopping potential:
A) Is doubled
B) Is quadrupled
C) Increases, but not necessarily doubled
D) Remains the same
5. Which of the following statements is true regarding the photoelectric effect?
A) The threshold frequency depends on the intensity of light.
B) The maximum kinetic energy of emitted electrons depends on the intensity of light.
C) The threshold frequency is a characteristic property of the metal.
D) Photoelectric emission occurs after a noticeable time delay.
6. The intensity of light is related to the square of its:
A) Frequency
B) Amplitude
C) Wavelength
D) Energy
7. In Einstein's photoelectric equation, E_k = hf - Φ, the term 'hf' represents the:
A) Work function of the metal
B) Maximum kinetic energy of the emitted electron
C) Energy of the incident photon
D) Threshold energy of the metal
8. If the work function of a metal is 2.5 eV, what is the minimum wavelength of light that can cause photoemission?
A) 496 nm
B) 248 nm
C) 400 nm
D) 620 nm
9. The photoelectric effect is a quantum phenomenon because:
A) It involves the exchange of energy in discrete packets (photons).
B) It demonstrates the wave nature of light.
C) It occurs only at very low temperatures.
D) It explains the emission of continuous spectra.
10. If the threshold frequency for a metal is 8.0 x 10^14 Hz, what is the work function?
A) 3.3 eV
B) 8.0 eV
C) 5.3 eV
D) 1.65 eV
11. Which quantity is conserved in the photoelectric effect?
A) Momentum of individual photons
B) Kinetic energy of individual electrons
C) Number of photons
D) Energy
12. The slope of the graph of stopping potential (V_s) versus frequency (f) of incident light is:
A) h
B) h/e
C) Φ/e
D) e
13. If the work function of a metal is Φ, and incident photons have energy E, then for photoemission to occur, E must be:
A) Greater than Φ
B) Less than Φ
C) Equal to Φ
D) Less than or equal to Φ
14. What is the energy of a photon of green light with a frequency of 5.5 x 10^14 Hz?
A) 3.64 eV
B) 2.28 eV
C) 5.5 eV
D) 1.82 eV
15. The photoelectric effect is an example of the interaction of electromagnetic radiation with:
A) Atoms
B) Nuclei
C) Electrons
D) Protons
16. If the frequency of incident radiation is decreased below the threshold frequency, the photoelectric current:
A) Decreases
B) Increases
C) Becomes zero
D) Remains unaffected
17. The work function of a metal is 4.0 eV. If photons of energy 5.0 eV strike the metal, what is the maximum kinetic energy of the emitted photoelectrons?
A) 1.0 eV
B) 4.0 eV
C) 5.0 eV
D) 9.0 eV
18. Which experiment provided the first direct evidence for the existence of photons?
A) Young's double-slit experiment
B) Michelson-Morley experiment
C) Photoelectric effect
D) Compton scattering
19. If the threshold wavelength of a metal is λ_0, then the maximum kinetic energy of emitted electrons when light of wavelength λ (< λ_0) is incident is given by:
A) hc(λ - λ_0) / (λ * λ_0)
B) hc(λ_0 - λ) / (λ * λ_0)
C) hc(λ_0 - λ) / λ_0
D) hc(λ - λ_0) / λ
20. The stopping potential required to stop the emission of electrons from a metal is independent of:
A) Frequency of incident light
B) Intensity of incident light
C) Work function of the metal
D) Planck's constant
21. The maximum kinetic energy of emitted photoelectrons is plotted against the frequency of incident light. The slope of the graph is equal to:
A) h
B) h/e
C) Φ
D) e
22. If a metal surface emits photoelectrons when illuminated by blue light of wavelength 450 nm, it will also emit photoelectrons when illuminated by:
A) Green light of wavelength 550 nm
B) Red light of wavelength 650 nm
C) Ultraviolet light of wavelength 200 nm
D) Infrared light of wavelength 800 nm
23. The photoelectric effect cannot be explained by classical wave theory because:
A) Wave theory predicts emission of electrons regardless of frequency.
B) Wave theory predicts a time lag for electron emission.
C) Wave theory predicts that electron emission depends on intensity, not frequency.
D) All of the above
24. What is the maximum kinetic energy of photoelectrons emitted from a metal surface when light of frequency 1.0 x 10^15 Hz is incident on it, given that the work function is 2.0 eV?
A) 2.28 eV
B) 4.14 eV
C) 2.0 eV
D) 0.28 eV
25. The momentum of a photon of energy E is given by:
A) E/c
B) E*c
C) E/h
D) h/E
26. If the frequency of incident light is increased by a factor of 3, and the new frequency is still greater than the threshold frequency, the maximum kinetic energy of emitted electrons will:
A) Triple
B) Increase by a factor of 3, but not necessarily triple
C) Increase, but cannot be determined without knowing the original frequency
D) Remain the same
27. The threshold wavelength for a metal is 400 nm. What is its work function?
A) 3.1 eV
B) 1.55 eV
C) 4.0 eV
D) 0.31 eV
28. Which of the following statements about the photoelectric effect is INCORRECT?
A) The energy of emitted electrons depends on the intensity of incident light.
B) The energy of emitted electrons depends on the frequency of incident light.
C) The rate of emission of electrons depends on the intensity of incident light.
D) The photoelectric effect is an instantaneous process.
29. If the stopping potential is 2 V for a certain frequency of incident light, what is the maximum kinetic energy of the emitted photoelectrons?
A) 2 eV
B) 3.2 x 10^-19 J
C) 1 eV
D) 1.6 x 10^-19 J
30. The photoelectric effect is observed in:
A) Metals only
B) Non-metals only
C) Insulators only
D) Gases only
31. What is the threshold frequency for a metal with a work function of 3.0 eV?
A) 7.25 x 10^14 Hz
B) 7.25 x 10^15 Hz
C) 3.0 x 10^14 Hz
D) 3.0 x 10^15 Hz
32. According to Einstein's equation, if the frequency of incident light is equal to the threshold frequency, the maximum kinetic energy of emitted electrons is:
A) Maximum
B) Minimum
C) Zero
D) Equal to the work function
33. The unit of work function (Φ) is typically:
A) Joule (J)
B) Electronvolt (eV)
C) Watt (W)
D) Ampere (A)
34. If a metal has a work function of 2.3 eV, what is the minimum frequency of light required to cause photoemission?
A) 5.57 x 10^14 Hz
B) 5.57 x 10^15 Hz
C) 2.3 x 10^14 Hz
D) 2.3 x 10^15 Hz
35. The photoelectric effect provides evidence for the:
A) Wave nature of light
B) Particle nature of light
C) Wave-particle duality of matter
D) Quantization of energy
36. What is the value of Planck's constant (h)?
A) 6.626 x 10^-34 J s
B) 9.109 x 10^-31 kg
C) 1.602 x 10^-19 C
D) 3.0 x 10^8 m/s
37. The phenomenon of photoelectric emission is instantaneous, meaning:
A) There is a significant time lag between incidence of light and emission of electrons.
B) There is no time lag between incidence of light and emission of electrons.
C) The time lag depends on the intensity of light.
D) The time lag depends on the wavelength of light.
38. The work function (Φ) of a metal is typically in the range of:
A) 0.1 to 1 eV
B) 1 to 10 eV
C) 10 to 100 eV
D) 100 to 1000 eV
39. If the frequency of incident radiation is doubled, the maximum kinetic energy of emitted photoelectrons will:
A) Double
B) Quadruple
C) Increase, but not necessarily double
D) Remain the same
40. The threshold wavelength (λ_0) is related to the threshold frequency (ν_0) by:
A) λ_0 = c / ν_0
B) λ_0 = ν_0 / c
C) λ_0 = c * ν_0
D) λ_0 = 1 / (ν_0 * c)
41. In the photoelectric effect, if the intensity of incident light is increased (keeping frequency constant), what happens to the photoelectric current?
A) Increases
B) Decreases
C) Remains the same
D) Becomes zero
42. In the photoelectric effect, if the intensity of incident light is increased (keeping frequency constant), what happens to the kinetic energy of emitted electrons?
A) Increases
B) Decreases
C) Remains the same
D) Becomes zero
43. The work function of a metal depends on:
A) The frequency of incident light
B) The intensity of incident light
C) The nature of the metal surface
D) The temperature of the incident light
44. What is the relationship between stopping potential (V_s) and the maximum kinetic energy (E_k) of emitted electrons?
A) E_k = e V_s
B) E_k = V_s / e
C) E_k = e / V_s
D) E_k = V_s
45. The stopping potential (V_s) in the photoelectric effect is the potential required to:
A) Increase the kinetic energy of emitted electrons.
B) Reduce the kinetic energy of emitted electrons to zero.
C) Increase the number of emitted electrons.
D) Decrease the work function of the metal.
46. If the frequency of incident light is less than the threshold frequency, what happens to the photoelectric emission?
A) Electrons are emitted with high kinetic energy.
B) Electrons are emitted with low kinetic energy.
C) No electrons are emitted.
D) The intensity of emitted electrons increases.
47. Einstein's photoelectric equation is given by E_k = hf - Φ. What does Φ represent?
A) Kinetic energy of the electron
B) Energy of the photon
C) Work function of the metal
D) Frequency of the incident light
48. The energy of a photon is directly proportional to its:
A) Wavelength
B) Frequency
C) Amplitude
D) Intensity
49. What is the minimum frequency of incident radiation required to eject electrons from a metal surface called?
A) Maximum frequency
B) Threshold frequency
C) Average frequency
D) Cut-off frequency
50. Who explained the photoelectric effect using the quantum theory of light?
A) Max Planck
B) Albert Einstein
C) Niels Bohr
D) Louis de Broglie
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