Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit
Astrophysics
156 practice questions
Topics covered
Practice questions
51–60 of 78 · Normal
Question 51
3 marks · Normal
Answer and see the solution →A star cools from 10,000 K to 4,000 K as it becomes a red giant. By what factor has the surface temperature changed? Give your answer to 2 significant figures.
Question 52
6 marks · Normal
Answer and see the solution →A student studies two stars: Alpha (surface temperature 3400 K) and Beta (surface temperature 8500 K). Both are located at the same distance from Earth and have the same luminosity.
(a)[2 marks]State the colour you would expect to see from each star based on their surface temperature.
(b)[2 marks]Classify each star using the star classification table.
(c)[2 marks]If both stars appear equally bright from Earth, describe what conclusions can be made about their absolute magnitude and their position in the Hertzsprung–Russell (HR) diagram.
Question 53
5 marks · Normal
Answer and see the solution →The table below shows data for three stars: Sirius, Betelgeuse, and Rigel. All three are located in the Milky Way.
Data for several stars Star Class Surface temperature (K) Sirius A 9500 Betelgeuse M 3200 Rigel B 12100 (a)[3 marks]For each star, state the likely colour you would observe.
(b)[2 marks]Describe the likely stage in the stellar life cycle for Betelgeuse and Rigel, based on their classification.
Question 54
5 marks · Normal
Answer and see the solution →An astronomer observes a distant galaxy and finds a star that is much more massive than the Sun. The star's surface temperature is 30,000 K, and it emits mostly blue light.
(a)[2 marks]Using the star classification table, state the spectral class of this star and its likely colour.
(b)[3 marks]Describe the final stages in the life of a star with much greater mass than the Sun, including possible remnants.
Question 55
4 marks · Normal
Answer and see the solution →When astronomers observe a distant galaxy through a telescope, they analyse its light spectrum to investigate its movement.
(a)[1 mark]State what is meant by red-shift in the context of light from galaxies.
(b)[2 marks]Explain what the observation of red-shifted light tells astronomers about the motion of distant galaxies.
(c)[1 mark]Describe how the size of the observed red-shift relates to the distance of a galaxy from Earth.
Question 56
3 marks · Normal
Answer and see the solution →Explain how the observation of red-shifted light from distant galaxies provides evidence for the Big Bang theory.
Question 57
1 mark · Normal
Answer and check →Which of the following is direct evidence that the universe is expanding?
- A.The cosmic microwave background radiation
- B.Observing galaxies with a blue-shift
- C.Red-shift in the light from distant galaxies
- D.The formation of supernovae
Question 58
2 marks · Normal
Answer and see the solution →A student incorrectly states that the blue-shift of galaxy light proves the universe is expanding. Explain why this statement is incorrect.
Question 59
4 marks · Normal
Answer and see the solution →The diagram shows lines on the spectrum of light from two galaxies, Q and R, at different observed wavelengths.
(a)[2 marks]State which galaxy, Q or R, is moving away from Earth faster. Justify your answer using the spectrum diagram.
(b)[2 marks]The normal wavelength of a particular line in a laboratory is 590 nm. For Galaxy Q, this line is observed at 594 nm. For Galaxy R, it is observed at 600 nm. Calculate the change in wavelength () for both galaxies.
Question 60
3 marks · Normal
Answer and see the solution →A sodium lamp on Earth emits a spectral line with a wavelength of 589 nm. The same line from a distant galaxy is observed at 600 nm.
Calculate the red-shift () of light from this galaxy. Use:\n\[ z = \frac{\Delta \lambda}{\lambda_0} \] where is the original wavelength.