A computer simulation predicts the observed wavelength of the same spectral line from two distant galaxies. Galaxy M is further from the Earth than galaxy N.
The wavelength of the spectral line in the laboratory is 500 nm500\ \mathrm{nm}500 nm.
The table shows four possible outputs from the simulation.
| Output | Observed wavelength from galaxy N in nm | Observed wavelength from galaxy M in nm |
|---|---|---|
| 1 | 506 | 518 |
| 2 | 518 | 506 |
| 3 | 512 | 512 |
| 4 | 494 | 482 |
Using the general relationship between red-shift and distance, which output is consistent with observations of distant galaxies?
Output 1
Output 3
Output 4
Output 2
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.