The cosmic microwave background radiation has a wavelength of 1.1 × 10-3 m. A numerical model predicts that, during a later period, the expansion of space stretches this wavelength by a factor of 1.6. Electromagnetic radiation travels through space at 3.0 × 108 m/s.
Calculate the frequency of the radiation at the end of this later period.
A student concludes that the radiation travels faster at the end of the period because its wavelength has increased.
Explain why the student's conclusion is incorrect.
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.