During a cosmological survey, the redshift z z\,z of several distant galaxies is plotted against their distance d d\,d from Earth.
Explain how the observation of redshift in these galaxies, and its relationship with distance, provides evidence for the expansion of the Universe.
53 exam-style questions on Edexcel GCSE Physics 7.2 The Universe and red-shift, covering 7.2.1 Big Bang and Steady State theories, 7.2.2 Evidence for the Big Bang, 7.2.3 The Doppler effect and red-shift, 7.2.4 Red-shift as evidence for an expanding Universe, and 7.2.5 The CMB and the accepted model. Each one has a worked solution and a mark scheme showing where the marks go.