Astronomy and cosmology — AS & A Level Physics (9702) questions by topic
Astronomy and cosmology covers stating Hubble's law and Wien's displacement law, explaining how redshift implies an expanding universe, and interpreting a distant galaxy's hydrogen emission spectrum, weighted from 8 to 12 marks in A Level Physics.
Calculate, state and explain dominate the command words, with draw and deduce also common: explain the mechanism linking redshift to recessional velocity, not just name the effect. This page holds 11 real questions from 2023 to 2025 papers. Submitting each answer for instant marking catches a standard-candle idea confused with a luminosity value, or an unshifted wavelength mixed up with a shifted one, before both slip into a full paper.
What examiners look for
- Examiners repeatedly find candidates state a different luminosity rather than specifically a higher luminosity when explaining why a star appears brighter.
- A recurring criticism is treating a standard candle as if it were a luminosity, a unit, or a measuring device rather than the concept it is.
- A common mistake is using the Doppler equation but assuming the larger wavelength is the unshifted one, or omitting to show the substitution of the speed of light.
- Reports flag some candidates mixing up Hubble's law with Wien's displacement law, or using the speed of light instead of recessional speed in the Hubble equation.
- Strong answers correctly recognise that a galaxy is moving away from Earth and work through the two-step redshift calculation accurately.
May–June 2025, Paper 41
May–June 2025, Paper 43
May–June 2024, Paper 41
State what is meant by the luminosity of a star.
Answer this question and get it marked →May–June 2024, Paper 42
Fig. 8.1 shows part of the emission spectrum of visible radiation emitted by hydrogen gas in a star in a distant galaxy. The galaxy is moving away from the Earth at a speed of 6.2…
Answer this question and get it marked →May–June 2024, Paper 43
State what is meant by the luminosity of a star.
Answer this question and get it marked →October–November 2024, Paper 41
Explain how redshift leads to the idea that the Universe is expanding.
Answer this question and get it marked →October–November 2024, Paper 43
Explain how redshift leads to the idea that the Universe is expanding.
Answer this question and get it marked →February–March 2023, Paper 42
A student observes different stars from the Earth. Give two reasons why some stars appear brighter than others.
Answer this question and get it marked →May–June 2023, Paper 41
State Hubble's law. Identify any symbols that you use.
Answer this question and get it marked →May–June 2023, Paper 43
State Hubble's law. Identify any symbols that you use.
Answer this question and get it marked →October–November 2023, Paper 42
State Wien's displacement law. Identify any symbols that you use.
Answer this question and get it marked →Other AS & A Level Physics topics
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