Lesson 5.6.2

5.6.2 Photoelectric effect, threshold frequency and work function Quiz: Pearson Edexcel Physics, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.6.2, Photoelectric effect, threshold frequency and work function: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 5: Waves and Particle Nature of Light, written with Revision Ninja.

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The 20 questions

  1. What is photoelectric emission?

    • The emission of X-rays when electrons strike a metal target
    • The emission of electrons from a metal surface when electromagnetic radiation of sufficiently high frequency is incident on it
    • The emission of light from a metal when it is heated
    • The absorption of electrons by a metal when light is reflected from it

  2. What is the threshold frequency for a metal surface?

    • The frequency at which the maximum kinetic energy of electrons is greatest
    • The minimum frequency of incident radiation that can cause photoelectron emission
    • The frequency of the most intense light that a metal can absorb
    • The frequency at which electrons are emitted fastest

  3. What is the work function of a metal?

    • The maximum kinetic energy of the emitted electrons
    • The energy of a photon at the threshold frequency
    • The energy stored in the lattice of the metal
    • The minimum energy needed to remove an electron from the surface of the metal

  4. Which equation is Einstein's photoelectric equation?

    • hf = phi - (1/2) m v_max^2
    • hf = phi/2 + (1/2) m v_max^2
    • h lambda = phi + m v_max
    • hf = phi + (1/2) m v_max^2

  5. When the intensity of light above the threshold frequency is increased, what happens?

    • The threshold frequency decreases
    • The work function of the metal increases
    • Their maximum kinetic energy increases, but the number emitted is unchanged
    • More photoelectrons are emitted per second, but their maximum kinetic energy is unchanged

  6. Why does the photoelectric effect provide evidence for the particle model of light?

    • The emission rate depends only on the wavelength of the light
    • Electrons are always emitted with the same energy whatever the frequency
    • Electrons are emitted after a delay that depends only on the intensity
    • Emission is almost instantaneous and occurs only above a threshold frequency, regardless of intensity, which the wave model cannot explain

  7. In a graph of maximum kinetic energy of photoelectrons against frequency of incident light, what does the gradient represent?

    • The threshold frequency
    • The work function of the metal
    • The stopping voltage
    • The Planck constant h

  8. A metal has work function 2.3 eV. What is its threshold frequency? Take h = 6.63 x 10^-34 J s and 1 eV = 1.6 x 10^-19 J.

    • 3.5 x 10^14 Hz
    • 1.4 x 10^15 Hz
    • 5.6 x 10^14 Hz
    • 5.6 x 10^12 Hz

  9. A metal with work function 2.0 eV is illuminated by light of frequency 1.0 x 10^15 Hz. What is the maximum kinetic energy of the emitted electrons? Take h = 6.63 x 10^-34 J s.

    • 1.0 x 10^-19 J
    • 3.4 x 10^-19 J
    • 6.6 x 10^-19 J
    • 3.2 x 10^-19 J

  10. The maximum kinetic energy of photoelectrons from a metal is 3.0 eV. What stopping potential is needed to stop them?

    • 1.5 V
    • 0.33 V
    • 3.0 V
    • 6.0 V

  11. What is the work function of a metal whose threshold wavelength is 500 nm? Use hc = 1240 eV nm.

    • 2.5 eV
    • 0.40 eV
    • 1.6 eV
    • 5.0 eV

  12. A metal surface is illuminated above its threshold frequency. The intensity of the light is doubled, with frequency unchanged. What is the effect?

    • The maximum kinetic energy doubles, while the number emitted is unchanged
    • The number of electrons emitted per second doubles, while the maximum kinetic energy is unchanged
    • Both the number emitted and the maximum kinetic energy double
    • Neither the number emitted nor the maximum kinetic energy changes

  13. Light below the threshold frequency of a metal has its intensity increased 100 times. What happens?

    • Electrons are emitted, but only after the intensity is increased 100 times
    • Electrons are emitted with the same energy as before
    • Electrons are emitted slowly, after a delay
    • No electrons are emitted, because each photon lacks the energy to overcome the work function

  14. On a graph of maximum kinetic energy of photoelectrons against frequency, the line crosses the frequency axis at 5.0 x 10^14 Hz. What does this crossing point represent?

    • The threshold frequency of the metal
    • The stopping voltage in volts
    • The charge of an electron in coulombs
    • The Planck constant of the metal

  15. A metal with work function 2.0 eV emits photoelectrons with maximum kinetic energy 1.1 eV when illuminated by light of wavelength 400 nm. Is this consistent with Einstein's equation? Use hc = 1240 eV nm.

    • Yes, because the maximum kinetic energy should equal the photon energy
    • Yes, because hc/lambda is 3.1 eV and 3.1 - 2.0 = 1.1 eV
    • No, because the maximum kinetic energy should equal the work function
    • No, because photons of 400 nm carry no energy

  16. Light of frequency f is incident on a metal with work function 3.0 eV, and the photoelectrons have maximum kinetic energy 2.0 eV. What is f?

    • 1.2 x 10^15 Hz
    • 6.0 x 10^14 Hz
    • 7.5 x 10^14 Hz
    • 2.0 x 10^15 Hz

  17. A student measures a stopping voltage of 0.50 V at frequency 6.0 x 10^14 Hz and 1.30 V at 8.0 x 10^14 Hz. Which value of h follows from the gradient of V against f? Use e = 1.6 x 10^-19 C.

    • 6.4 x 10^-34 J s
    • 3.2 x 10^-34 J s
    • 1.6 x 10^-19 J s
    • 6.4 x 10^-19 J s

  18. A metal has threshold wavelength 620 nm. What is the maximum kinetic energy of electrons emitted by light of wavelength 450 nm? Use hc = 1240 eV nm.

    • About 0.40 eV
    • About 2.8 eV
    • About 0.76 eV
    • About 1.2 eV

  19. Why does maximum kinetic energy of photoelectrons increase with frequency, rather than with intensity?

    • Electrons absorb many photons, so intensity sets their energy
    • The work function of the metal depends on the intensity of the light
    • Each electron absorbs one photon, so its energy depends on hf, while intensity only sets how many photons arrive
    • Intensity sets the energy per electron, while frequency sets how many electrons are emitted

  20. A student says that light of greater intensity always makes the emitted electrons leave with more energy. Which evaluation is correct?

    • Incorrect, because intensity changes the number of electrons emitted, while maximum kinetic energy depends on frequency
    • Incorrect, because intensity has no effect on the emission at all
    • Correct, because more photons always make electrons faster
    • Correct, because more intense light carries more energy per photon

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