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Edexcel IGCSE Physics 8.18P Expansion of the universe

Practise explaining how galaxy red-shift and Hubble-style graphs support an expanding universe and the Big Bang model.

Syllabus
First assessment 2019
Course
Physics 4PH1

Exam points

  • interpret a graph showing wavelength change or velocity increasing with distance
  • explain that greater red-shift in distant galaxies shows the universe is expanding
  • link galaxies moving apart now to matter being closer together in the past

8.18P Expansion of the universe question 1

[Maximum number: 2]

Between 1929 and 1931, physicists Hubble and Humason investigated the red-shift of light from galaxies at different distances from the Earth.

The distance unit they used is the megaparsec (Mpc).

The graph shows some of the results of their investigation.

Figure for Question 8.18P Expansion of the universe question 1 — Edexcel IGCSE Physics

Explain why the graph from Hubble's investigation provides evidence for the expansion of the universe.

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