Spectral lines from most distant galaxies are shifted towards longer wavelengths.
What does this observation indicate?
The galaxies are moving towards the Earth.
The galaxies emit light at a decreasing speed.
The galaxies are moving away from the Earth.
The galaxies emit light at an increasing speed.
94 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.