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Cosmology: OCR A‑Level Physics A questions

Every OCR A-Level Physics A exam question on 5.5.3 Cosmology, 2016–2025, with its mark scheme and examiner’s report.

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1,877 questions

  1. Q7

    June 2025 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2025 Paper 1, question 7: The apparent position of a star changes by an angle of 1.0 × 10– 4 degrees between observations 7 made 6 months apart from the same place on Earth. What is the

  2. Q15

    June 2025 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2025 Paper 1, question 15: Which of these statements about the Universe is implied by the Cosmological principle? A Dark energy is found in every galaxy B Kepler’s laws can be applied to

  3. Q23(a)

    June 2025 · Paper 1

    3 marks5.5.3 Cosmology
    The whole paper ↗
    June 2025 Paper 1, question 23(a): Calculate the magnitude of the recession velocity of M87. velocity = km s–1 [3]

  4. Q23(b)

    June 2025 · Paper 1

    2 marks5.5.3 Cosmology
    The whole paper ↗
    June 2025 Paper 1, question 23(b): Estimate the distance in light years to M87 using Hubble’s law. Hubbles constant Ho = 2.5 × 10–19 s–1 distance = ly [2]

  5. Q23(c)

    June 2025 · Paper 1

    2 marks5.5.3 Cosmology2.2.1 Measurements and uncertainties
    The whole paper ↗
    June 2025 Paper 1, question 23(c): Estimate the percentage uncertainty in the distance calculated in part (b) using the width of the emission line in the diagram. percentage uncertainty = +/– % [

  6. Q23(d)

    June 2025 · Paper 1

    2 marks5.5.3 Cosmology
    The whole paper ↗
    June 2025 Paper 1, question 23(d): Other methods have shown M87 is actually 50 million light years from Earth. Suggest why M87 might contradict Hubble’s law. [2]

  7. Q23(e)

    June 2025 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2025 Paper 1, question 23(e): Suggest one reason why the Big Bang theory is still the accepted model of the origin of the Universe. [1]

  8. Q15

    June 2024 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2024 Paper 1, question 15: Stars rotate around the centre of their galaxy. Observations suggest that the stars at the edges of galaxies are moving at much higher velocities than expected.

  9. Q23(b)(ii)

    June 2024 · Paper 1

    2 marks5.5.3 Cosmology
    The whole paper ↗
    June 2024 Paper 1, question 23(b)(ii): Calculate the recession velocity v of the galaxy. v = m s–1 [2]

  10. Q23(b)(iii)

    June 2024 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2024 Paper 1, question 23(b)(iii): State the name of the theory that is supported by evidence from the measurement of the recession velocities of galaxies in the universe. [1]

  11. Q13

    June 2023 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2023 Paper 1, question 13: During the evolution of the universe there was a period of inflation. Which forms of matter, if any, existed 10 –10 s after the big bang? A Atoms B Leptons C No

  12. Q14

    June 2023 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2023 Paper 1, question 14: Part of the emission spectrum for hydrogen in a laboratory is shown. All wavelengths are given in nm. 434 486 430 500 Which diagram shows the corresponding part

  13. Q15

    June 2023 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2023 Paper 1, question 15: An early estimate for the Hubble constant was 500 km s–1 Mpc–1. What is the value of this estimate in units of s–1? 1 parsec = 3.1 × 1016 m 2.3 × 10–18 A 1.6 ×

  14. Q23(a)(i)

    June 2023 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2023 Paper 1, question 23(a)(i): Estimate the maximum stellar distance in parsecs that could be measured using Hipparcos. maximum stellar distance = pc [1]

  15. Q23(a)(ii)

    June 2023 · Paper 1

    2 marks5.5.3 Cosmology2.2.1 Measurements and uncertainties
    The whole paper ↗
    June 2023 Paper 1, question 23(a)(ii): Calculate the percentage uncertainty in the calculated value of the distance to Polaris A. percentage uncertainty = % [2]

  16. Q3(c)(ii)

    June 2023 · Paper 3

    3 marks4.4.1 Wave motion5.5.3 Cosmology
    The whole paper ↗
    June 2023 Paper 3, question 3(c)(ii): The surface area of the telescope is about 3000 m2. The distance to the pulsar is about 300 pc. By assuming that the radiation from the pulsar is emitted equall

  17. Q13

    June 2022 · Paper 1

    1 mark5.5.3 Cosmology4.4.3 Superposition
    The whole paper ↗
    June 2022 Paper 1, question 13: Light from a hydrogen source is incident normally at a diffraction grating. The first order maximum of the H-alpha spectral line of wavelength 486 nm is observe

  18. Q14

    June 2022 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2022 Paper 1, question 14: A galaxy, 1.0 × 109 light-years away from the Earth, has a recession speed of 23 000 km s–1. Which expression, based on the information above, is correct for th

  19. Q15

    June 2022 · Paper 1

    1 mark5.5.3 Cosmology
    The whole paper ↗
    June 2022 Paper 1, question 15: Astronomers observe approximately the same number of distant galaxies per unit volume of space in all directions. Which idea does this observation support? A Bi

  20. Q21(b)(i)

    June 2022 · Paper 1

    2 marks5.5.3 Cosmology
    The whole paper ↗
    June 2022 Paper 1, question 21(b)(i): Show that the volume of the nebula is 4.1 × 1051 m3. 1 pc = 3.1 × 1016 m [2]
All 43 questions on Cosmology, as a list
  1. June 2025, Paper 1, Q7 (1 mark): The apparent position of a star changes by an angle of 1.0 × 10– 4 degrees between observations 7 made 6 months apart from the same place on Earth. What is the
  2. June 2025, Paper 1, Q15 (1 mark): Which of these statements about the Universe is implied by the Cosmological principle? A Dark energy is found in every galaxy B Kepler’s laws can be applied to
  3. June 2025, Paper 1, Q23(a) (3 marks): Calculate the magnitude of the recession velocity of M87. velocity = km s–1 [3]
  4. June 2025, Paper 1, Q23(b) (2 marks): Estimate the distance in light years to M87 using Hubble’s law. Hubbles constant Ho = 2.5 × 10–19 s–1 distance = ly [2]
  5. June 2025, Paper 1, Q23(c) (2 marks): Estimate the percentage uncertainty in the distance calculated in part (b) using the width of the emission line in the diagram. percentage uncertainty = +/– % [
  6. June 2025, Paper 1, Q23(d) (2 marks): Other methods have shown M87 is actually 50 million light years from Earth. Suggest why M87 might contradict Hubble’s law. [2]
  7. June 2025, Paper 1, Q23(e) (1 mark): Suggest one reason why the Big Bang theory is still the accepted model of the origin of the Universe. [1]
  8. June 2024, Paper 1, Q15 (1 mark): Stars rotate around the centre of their galaxy. Observations suggest that the stars at the edges of galaxies are moving at much higher velocities than expected.
  9. June 2024, Paper 1, Q23(b)(ii) (2 marks): Calculate the recession velocity v of the galaxy. v = m s–1 [2]
  10. June 2024, Paper 1, Q23(b)(iii) (1 mark): State the name of the theory that is supported by evidence from the measurement of the recession velocities of galaxies in the universe. [1]
  11. June 2023, Paper 1, Q13 (1 mark): During the evolution of the universe there was a period of inflation. Which forms of matter, if any, existed 10 –10 s after the big bang? A Atoms B Leptons C No
  12. June 2023, Paper 1, Q14 (1 mark): Part of the emission spectrum for hydrogen in a laboratory is shown. All wavelengths are given in nm. 434 486 430 500 Which diagram shows the corresponding part
  13. June 2023, Paper 1, Q15 (1 mark): An early estimate for the Hubble constant was 500 km s–1 Mpc–1. What is the value of this estimate in units of s–1? 1 parsec = 3.1 × 1016 m 2.3 × 10–18 A 1.6 ×
  14. June 2023, Paper 1, Q23(a)(i) (1 mark): Estimate the maximum stellar distance in parsecs that could be measured using Hipparcos. maximum stellar distance = pc [1]
  15. June 2023, Paper 1, Q23(a)(ii) (2 marks): Calculate the percentage uncertainty in the calculated value of the distance to Polaris A. percentage uncertainty = % [2]
  16. June 2023, Paper 3, Q3(c)(ii) (3 marks): The surface area of the telescope is about 3000 m2. The distance to the pulsar is about 300 pc. By assuming that the radiation from the pulsar is emitted equall
  17. June 2022, Paper 1, Q13 (1 mark): Light from a hydrogen source is incident normally at a diffraction grating. The first order maximum of the H-alpha spectral line of wavelength 486 nm is observe
  18. June 2022, Paper 1, Q14 (1 mark): A galaxy, 1.0 × 109 light-years away from the Earth, has a recession speed of 23 000 km s–1. Which expression, based on the information above, is correct for th
  19. June 2022, Paper 1, Q15 (1 mark): Astronomers observe approximately the same number of distant galaxies per unit volume of space in all directions. Which idea does this observation support? A Bi
  20. June 2022, Paper 1, Q21(b)(i) (2 marks): Show that the volume of the nebula is 4.1 × 1051 m3. 1 pc = 3.1 × 1016 m [2]
  21. June 2022, Paper 3, Q4(a) (2 marks): Describe the origin of the microwave background radiation. [2]
  22. November 2021, Paper 1, Q5 (1 mark): A spectral line corresponds to a wavelength λ1 in the laboratory. The same spectral line observed in the spectrum of a receding galaxy corresponds to a waveleng
  23. November 2021, Paper 1, Q15 (1 mark): The parallax angle for a star is 0.015 seconds of arc. What is the distance in parsecs (pc) of the star from the Earth? A 67 pc B 133 pc C 220 pc 2.1 × 1018 pc
  24. November 2020, Paper 1, Q7 (1 mark): Recent analysis of the data collected from the Hubble and Gaia telescopes gave the Hubble constant a value of 73.5 km s–1 Mpc–1. What is this value, written to
  25. November 2020, Paper 1, Q11 (1 mark): In astronomy, distance can be measured in different units. Which one of the following distances is the largest? 4.22 × 1016 m A B 1.91 pc C 3.42 ly D 593 AU You
  26. June 2019, Paper 1, Q13 (1 mark): Which column A, B, C or D, shows the correct sequence for the evolution of the Universe between the Big Bang and the formation of stars? A B C D Universe starts
  27. June 2019, Paper 1, Q15 (1 mark): An astronomer analyses the light from a distant galaxy. One of the spectral lines in the spectrum observed from the galaxy has wavelength 610 nm. The same spect
  28. June 2019, Paper 1, Q24(a)(i) (2 marks): Show that the parallax angle p for Proxima Centauri is about 0.8 arc second. [2] Question 24 continues on page 30
  29. June 2019, Paper 1, Q24(a)(ii) (2 marks): Use your answer in (i) to calculate the distance d of Proxima Centauri from the Earth in light-years (ly). 1 pc = 3.26 ly d = ly [2]
  30. June 2019, Paper 1, Q24(b)(ii) (1 mark): Show that the mean density of the Universe is about 7 × 10–29 kg m–3. [1]
  31. June 2019, Paper 1, Q24(b)(iii) (1 mark): Suggest why the actual mean density of the Universe is different from the value calculated in (ii). [1]
  32. June 2019, Paper 3, Q6(a) (1 mark): Describe the Doppler effect. [1]
  33. June 2019, Paper 3, Q6(c)(ii) (2 marks): The speed of sound in this experiment is 330 m s–1. Calculate the maximum change in frequency Δf of the sound detected by the microphone. Δf = Hz [2]
  34. June 2019, Paper 3, Q6(c)(iii) (1 mark): Hence complete the scale on the y-axis of Fig. 6.2. [1]
  35. June 2019, Paper 3, Q6(c)(iv) (1 mark): Mark with an X on Fig. 6.1 the position of the loudspeaker which corresponds to the point X on Fig. 6.2. [1]
  36. June 2018, Paper 1, Q23(a) (1 mark): According to the Cosmological principle, the Universe is isotropic, homogeneous and the laws of physics are universal. State what is meant by the term homogeneo
  37. June 2018, Paper 1, Q23(b)(i) (3 marks): Calculate in nm the wavelength λ of the same spectral line from RXJ1242-11 when observed from the Earth. Assume the Hubble constant is 68 km s−1 Mpc−1. λ = nm [
  38. June 2018, Paper 1, Q23(c) (4 marks): The Universe evolved from the Big Bang. Describe the evolution of the Universe up to the formation of the first nuclei. [4]
  39. June 2018, Paper 3, Q3(a)(iii) (2 marks): The stars are viewed from Earth in the plane of rotation. The stars are observed using light that has wavelength of 656 nm in the laboratory. The observed light
  40. June 2017, Paper 1, Q15 (1 mark): Which two quantities are related in Hubble’s law? A Distance and mass of galaxies. B Velocity and intensity of galaxies. C Distance and velocity of galaxies. D
  41. June 2017, Paper 1, Q21(b)(iii) (3 marks): In the laboratory, the wavelength of the hydrogen-alpha emission line is 656.3 nm. Use Fig. 21.2 to determine the recession velocity of the galaxy. recession ve
  42. June 2017, Paper 1, Q21(b)(iv) (1 mark): Suggest why hydrogen spectral lines play an important role in determining red shift of galaxies. [1]
  43. June 2017, Paper 1, Q21(c) (3 marks): Light from a similar star is viewed in a galaxy further away. The star is part of a pair of stars which orbit a common centre of mass. Describe and explain how

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