An astronomer compares light from two galaxies, R and S, with light from a laboratory source. Galaxy R looks redder overall than galaxy S. The table shows the wavelengths of the same two spectral lines in each case.
| Spectral line | Laboratory wavelength (nm) | Galaxy R wavelength (nm) | Galaxy S wavelength (nm) |
|---|---|---|---|
| 1 | 486 | 491 | 510 |
| 2 | 656 | 663 | 688 |
Explain which galaxy is receding faster, and why the overall colour of each galaxy does not affect your answer.
79 exam-style questions on AQA GCSE Physics 8.2 Red-shift, covering 8.2 Red-shift. Each one has a worked solution and a mark scheme showing where the marks go.