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Lasers: Eduqas A‑Level Physics questions

Every Eduqas A-Level Physics exam question on 3.5 Lasers, 2016–2025, with its mark scheme and examiner’s report.

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1,592 questions

  1. Q7(a)

    June 2025 · Component 3

    6 marks3.5 Lasers
    The whole paper ↗
    June 2025 Component 3, question 7(a): Explain how a 3-level laser system works. Include an explanation of the role of the amplifying medium. [6 QER] 3-level system E3 exiting laser beam E2 100% ampl

  2. Q7(b)

    June 2025 · Component 3

    2 marks3.5 Lasers
    The whole paper ↗
    June 2025 Component 3, question 7(b): Semiconductor lasers are used in many applications because they are far more efficient than gas lasers. State one use and another advantage of semiconductor las

  3. Q5(a)(i)

    June 2024 · AS Component 2

    1 mark3.5 Lasers
    The whole paper ↗
    June 2024 AS Component 2, question 5(a)(i): State the transition associated with pumping. [1]

  4. Q5(a)(ii)

    June 2024 · AS Component 2

    3 marks3.5 Lasers
    The whole paper ↗
    June 2024 AS Component 2, question 5(a)(ii): Explain why a population inversion is required for a laser to work. [3]

  5. Q5(b)

    June 2024 · AS Component 2

    4 marks3.5 Lasers
    The whole paper ↗
    June 2024 AS Component 2, question 5(b): The manufacturer’s label shows that the wavelength of the light from the laser is 630 nm. Determine whether this label is correct. [4]

  6. Q6(a)

    June 2023 · Component 3

    1 mark3.5 Lasers
    The whole paper ↗
    June 2023 Component 3, question 6(a): State what is meant by a metastable energy level. [1]

  7. Q6(b)

    June 2023 · Component 3

    3 marks3.5 Lasers3.6 Nuclear decay
    The whole paper ↗
    June 2023 Component 3, question 6(b): If the half-life of the metastable energy level is 2.4 ms, explain why the equilibrium number of electrons in the metastable energy level is approximately 1.7 ×

  8. Q6(c)

    June 2023 · Component 3

    3 marks3.5 Lasers
    The whole paper ↗
    June 2023 Component 3, question 6(c): Hence, explain why it is desirable for the metastable state in a laser system to have a long half-life. [3]

  9. Q4(c)

    June 2022 · AS Component 2

    4 marks3.5 Lasers
    The whole paper ↗
    June 2022 AS Component 2, question 4(c): Explain why a population inversion, metastable state and stimulated emission are required for a laser to work. [4]

  10. Q4(a)

    Autumn 2020 · Component 3

    2 marks3.5 Lasers
    The whole paper ↗
    Autumn 2020 Component 3, question 4(a): Explain what is meant by stimulated emission of radiation. [2]

  11. Q4(b)

    Autumn 2020 · Component 3

    2 marks3.5 Lasers
    The whole paper ↗
    Autumn 2020 Component 3, question 4(b): The energy levels of a 4-level laser system are shown. 4-level system E3 E2 E1 E0 Give two reasons why energy level E1 is always nearly empty. [2]

  12. Q4(c)

    Autumn 2020 · Component 3

    3 marks3.5 Lasers
    The whole paper ↗
    Autumn 2020 Component 3, question 4(c): Victoria claims that when the laser system shown below is in equilibrium, the amplifying medium provides only a 0.5 % increase in intensity of the beam each tim

  13. Q3(a)(i)

    June 2019 · Component 3

    2 marks3.5 Lasers
    The whole paper ↗
    June 2019 Component 3, question 3(a)(i): Explain why a population inversion is not usually possible with a 2-level energy system pumped using light. [2]

  14. Q3(a)(ii)

    June 2019 · Component 3

    2 marks3.5 Lasers
    The whole paper ↗
    June 2019 Component 3, question 3(a)(ii): State an advantage of semiconductor lasers and an example of their use. [2]

  15. Q3(b)

    June 2019 · Component 3

    6 marks3.5 Lasers
    The whole paper ↗
    June 2019 Component 3, question 3(b): Explain how 3-level and 4-level laser systems work and the advantages of a 4-level system. Refer to the diagrams in your answer. [6 QER] 3-level system 4-level

  16. Q4(a)

    June 2018 · Component 3

    2 marks3.5 Lasers
    The whole paper ↗
    June 2018 Component 3, question 4(a): Explain the purpose of the 99.0% reflecting mirror and the 100.0% reflecting mirror. [2]

  17. Q4(b)

    June 2018 · Component 3

    3 marks3.5 Lasers
    The whole paper ↗
    June 2018 Component 3, question 4(b): Explain the purpose of a population inversion in the laser cavity. [3]

  18. Q5(a)

    June 2018 · AS Component 2

    6 marks3.5 Lasers
    The whole paper ↗
    June 2018 AS Component 2, question 5(a): Explain how a 3 level laser operates, explaining also why a 2 level laser is not possible. [6 QER]

  19. Q5(b)(i)

    June 2018 · AS Component 2

    2 marks3.5 Lasers
    The whole paper ↗
    June 2018 AS Component 2, question 5(b)(i): The wavelength of light from the laser is 633 nm. Calculate the energy of a photon of light emitted by the laser. [2]

  20. Q5(b)(ii)

    June 2018 · AS Component 2

    3 marks3.5 Lasers
    The whole paper ↗
    June 2018 AS Component 2, question 5(b)(ii): The power output of the laser is 1.0 mW. Mirror M2 transmits 1 in 500 photons. Determine the number of photons per second incident on mirror M2 [3]
All 29 questions on Lasers, as a list
  1. June 2025, Component 3, Q7(a) (6 marks): Explain how a 3-level laser system works. Include an explanation of the role of the amplifying medium. [6 QER] 3-level system E3 exiting laser beam E2 100% ampl
  2. June 2025, Component 3, Q7(b) (2 marks): Semiconductor lasers are used in many applications because they are far more efficient than gas lasers. State one use and another advantage of semiconductor las
  3. June 2024, AS Component 2, Q5(a)(i) (1 mark): State the transition associated with pumping. [1]
  4. June 2024, AS Component 2, Q5(a)(ii) (3 marks): Explain why a population inversion is required for a laser to work. [3]
  5. June 2024, AS Component 2, Q5(b) (4 marks): The manufacturer’s label shows that the wavelength of the light from the laser is 630 nm. Determine whether this label is correct. [4]
  6. June 2023, Component 3, Q6(a) (1 mark): State what is meant by a metastable energy level. [1]
  7. June 2023, Component 3, Q6(b) (3 marks): If the half-life of the metastable energy level is 2.4 ms, explain why the equilibrium number of electrons in the metastable energy level is approximately 1.7 ×
  8. June 2023, Component 3, Q6(c) (3 marks): Hence, explain why it is desirable for the metastable state in a laser system to have a long half-life. [3]
  9. June 2022, AS Component 2, Q4(c) (4 marks): Explain why a population inversion, metastable state and stimulated emission are required for a laser to work. [4]
  10. Autumn 2020, Component 3, Q4(a) (2 marks): Explain what is meant by stimulated emission of radiation. [2]
  11. Autumn 2020, Component 3, Q4(b) (2 marks): The energy levels of a 4-level laser system are shown. 4-level system E3 E2 E1 E0 Give two reasons why energy level E1 is always nearly empty. [2]
  12. Autumn 2020, Component 3, Q4(c) (3 marks): Victoria claims that when the laser system shown below is in equilibrium, the amplifying medium provides only a 0.5 % increase in intensity of the beam each tim
  13. June 2019, Component 3, Q3(a)(i) (2 marks): Explain why a population inversion is not usually possible with a 2-level energy system pumped using light. [2]
  14. June 2019, Component 3, Q3(a)(ii) (2 marks): State an advantage of semiconductor lasers and an example of their use. [2]
  15. June 2019, Component 3, Q3(b) (6 marks): Explain how 3-level and 4-level laser systems work and the advantages of a 4-level system. Refer to the diagrams in your answer. [6 QER] 3-level system 4-level
  16. June 2018, Component 3, Q4(a) (2 marks): Explain the purpose of the 99.0% reflecting mirror and the 100.0% reflecting mirror. [2]
  17. June 2018, Component 3, Q4(b) (3 marks): Explain the purpose of a population inversion in the laser cavity. [3]
  18. June 2018, AS Component 2, Q5(a) (6 marks): Explain how a 3 level laser operates, explaining also why a 2 level laser is not possible. [6 QER]
  19. June 2018, AS Component 2, Q5(b)(i) (2 marks): The wavelength of light from the laser is 633 nm. Calculate the energy of a photon of light emitted by the laser. [2]
  20. June 2018, AS Component 2, Q5(b)(ii) (3 marks): The power output of the laser is 1.0 mW. Mirror M2 transmits 1 in 500 photons. Determine the number of photons per second incident on mirror M2 [3]
  21. June 2017, Component 3, Q1(a) (2 marks): Label the pumping and stimulated emission transitions in the four and three level laser systems shown below. [2] E4 E3 E3 E2 E2 E1 E1
  22. June 2017, Component 3, Q1(b) (4 marks): Explain why a population inversion can be achieved far more easily in a four level system than in a three level system. [4]
  23. June 2017, Component 3, Q1(c) (2 marks): Give two reasons why the top level (E4 in the four level system and E3 in the three level system) must have a short lifetime. [2]
  24. June 2017, AS Component 2, Q7(a)(i) (1 mark): State what is meant by a population inversion. [1]
  25. June 2017, AS Component 2, Q7(a)(ii) (2 marks): Explain why a population inversion is needed for laser action. [2]
  26. June 2017, AS Component 2, Q7(b) (3 marks): Calculate the output wavelength of this naturally occurring laser and determine the region of the electromagnetic spectrum in which it lies. [3] FOR THE LAST PA
  27. June 2016, AS Component 2, Q5(b) (4 marks): Light from the Sun has intensity 1.36 kW m–2 on Earth and light from a standard laboratory laser has intensity 1.0 mW mm–2. Discuss with the aid of a calculatio
  28. June 2016, AS Component 2, Q5(c)(i) (3 marks): Describe how a photon is created by stimulated emission involving level U and level L. [3]
  29. June 2016, AS Component 2, Q5(c)(ii) (3 marks): Determine the energy of level U given that the wavelength of the light from the laser is 5.90 × 10–7 m. [3]

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