The table shows two spectral lines from the same element.
| Line | Laboratory wavelength in nm | Wavelength from a galaxy in nm |
|---|---|---|
| P | 400 | 420 |
| Q | 600 | 630 |
Which correctly compares the percentage increases in wavelength and identifies the shift?
Both increase by 5%5\%5%; the light is red-shifted.
Both increase by 5%5\%5%; the light is blue-shifted.
P increases by 20%20\%20% and Q by 30%30\%30%; the light is red-shifted.
P increases by 20%20\%20% and Q by 30%30\%30%; the light is blue-shifted.
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.