Astronomy and cosmology: past paper questions
Real questions on astronomy and cosmology
The newest 20 of 106 written questions. Open one to see it on the real paper.
- 9702/41 · October/November 2025 · Q9c[2]
Star X is in a galaxy that is moving away from the Earth. Suggest, with a reason, how the line for star X in Fig. 9.2 would appear differently if it had been obtained from data measured on the Earth.
See it on the paper → - 9702/42 · October/November 2025 · Q9c(i)[2]
Determine a value for the luminosity of Sirius. Give a unit with your answer. luminosity = unit
See it on the paper → - 9702/42 · October/November 2025 · Q9c(ii)[2]
Use your answer in (c)(i) to determine the surface temperature of Sirius. surface temperature = K
See it on the paper → - 9702/42 · October/November 2025 · Q9d[3]
Explain how cosmologists use standard candles to estimate the distance of a galaxy from the Earth.
See it on the paper → - 9702/43 · October/November 2025 · Q9b[3]
Fig. 9.1 shows the variation with d –2 of the radiant flux intensity F observed from a star X, where d is the distance of the observer from the star. Fig. 9.2 shows the variation with wavelength λ of the rates of emission P of radiation by star X and the Sun. 8 F / 10 3 W m –2 star X P 4 Sun 0 0 1 2 3 0 5 10 d –2 / 10...
See it on the paper → - 9702/43 · October/November 2025 · Q9c[2]
Star X is in a galaxy that is moving away from the Earth. Suggest, with a reason, how the line for star X in Fig. 9.2 would appear differently if it had been obtained from data measured on the Earth.
See it on the paper → - 9702/51 · October/November 2025 · Q2a[1]
A graph is plotted of λ on the y-axis against d on the x-axis. c Determine expressions for the gradient and y-intercept. gradient =
See it on the paper → - 9702/51 · October/November 2025 · Q2d[1]
Using your answers to (a), (c)(iii) and (c)(iv), determine the values of λ 0 and H. Include appropriate units. λ 0 =
See it on the paper → - 9702/51 · October/November 2025 · Q2e[2]
Hubble’s law suggests that the age T of the universe is related to H by T = 1 . H Determine a value for T. Include the absolute uncertainty in your answer. T = s
See it on the paper → - 9702/53 · October/November 2025 · Q2a[1]
A graph is plotted of λ on the y-axis against d on the x-axis. c Determine expressions for the gradient and y-intercept. gradient =
See it on the paper → - 9702/53 · October/November 2025 · Q2b[1]
Values of d and λ are given in Table 2.1. Table 2.1 0.48 ± 0.12 658.4 1.04 ± 0.12 661.2 1.45 ± 0.12 664.2 1.80 ± 0.12 665.7 2.85 ± 0.12 672.4 3.75 ± 0.12 678.2 λ / nm The value of c is 3.00 × 10 5 km s –1 . Calculate and record values of d d / 10 15 s in Table 2.1. Include the absolute uncertainties in . d / 10 15 s c...
See it on the paper → - 9702/53 · October/November 2025 · Q2c(i)[2]
Plot a graph of λ / nm against d d / 10 15 s. Include error bars for . c c
See it on the paper → - 9702/53 · October/November 2025 · Q2c(ii)[2]
Draw the straight line of best fit and a worst acceptable straight line on your graph. Label both lines.
See it on the paper → - 9702/53 · October/November 2025 · Q2c(iii)[2]
Determine the gradient of the line of best fit. Include the absolute uncertainty in your answer. gradient = 680 678 λ / nm 674 672 670 676 668 666 664 662 660 658 0 2 4 6 8 10 12 d / 10 15 s c 14
See it on the paper → - 9702/53 · October/November 2025 · Q2c(iv)[2]
Determine the y-intercept of the line of best fit. Include the absolute uncertainty in your answer. y-intercept = (iv)
See it on the paper → - 9702/53 · October/November 2025 · Q2d[1]
Using your answers to (a), (c)(iii) and (c)(iv), determine the values of λ 0 and H. Include appropriate units. λ 0 =
See it on the paper → - 9702/53 · October/November 2025 · Q2e[2]
Hubble’s law suggests that the age T of the universe is related to H by T = 1 . H Determine a value for T. Include the absolute uncertainty in your answer. T = s
See it on the paper → - 9702/41 · May/June 2025 · Q10a[2]
State Hubble’s law.
See it on the paper → - 9702/41 · May/June 2025 · Q10b(i)[2]
Explain why the observed wavelength and the emitted wavelength have different values.
See it on the paper → - 9702/41 · May/June 2025 · Q10b(ii)[2]
Calculate the speed of the star relative to the Earth. speed = m s –1
See it on the paper →
What examiners said
Candidates who knew the theory were generally able to give a full definition of luminosity, as the total radiant power of the star. Many responses were partial answers.
— Examiner report, February/March 2025, 9702/42 Q10(a)(i) (Cambridge)
Many full and accurate descriptions were seen in response to this question, which directly assesses the syllabus learning outcome concerning the use of standard candles to determine distances to galaxies. For full credit, candidates needed to establish how the information about luminosity and radiant flux intensity is established, and then how the equation linking them can be used to calculate the...
— Examiner report, February/March 2025, 9702/42 Q10(a)(ii) (Cambridge)
Most candidates knew that Wien’s displacement law involves a wavelength being inversely proportional to a temperature, but only the strongest candidates were able to correctly identify what, in the context of Wien’s law, is meant by wavelength and temperature. Common mistakes were to describe the wavelength as a ‘maximum wavelength’ and/or to omit that the temperature is the thermodynamic temperat...
— Examiner report, October/November 2023, 9702/42 Q10(a) (Cambridge)
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