A spectral line in the light from hydrogen in a laboratory has a frequency of 4.57 × 1014 Hz.
The speed of light is 3.0 × 108 m/s.
Calculate the wavelength of this spectral line in the laboratory.
In the light from a distant galaxy, the wavelength of the same spectral line is 6.89 × 10-7 m.
Calculate the frequency of this spectral line in the light from the galaxy.
Explain what your answers to (a) and (b) show about the motion of the galaxy.
A second galaxy is much further away than the first galaxy.
Predict how the change in wavelength of this spectral line for the second galaxy compares with the change for the first galaxy.
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.