Three distant galaxies show the same spectral line, whose laboratory wavelength is 500 nm500\ \mathrm{nm}500 nm.
| Galaxy | Observed wavelength in nm |
|---|---|
| P | 515 |
| Q | 505 |
| R | 530 |
Which conclusion agrees with both the spectral data and the general distance-speed relationship?
R recedes fastest; Q is expected to be nearest.
P recedes fastest; R is expected to be nearest.
Q recedes fastest; P is expected to be nearest.
R recedes fastest; P is expected to be nearest.
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.