An absorption line in the spectrum of light from a distant galaxy is observed at a wavelength of 525 nm525\text{ nm}525 nm. In a laboratory on Earth, the same absorption line is measured at a rest wavelength of 500 nm500\text{ nm}500 nm.
Which of the following correctly identifies the cosmological redshift z z\,z of this galaxy and the physical system whose expansion is supported by this observation?
Redshift z=0.048z = 0.048z=0.048; expansion of the Solar System
Redshift z=0.050z = 0.050z=0.050; expansion of the Universe
Redshift z=0.048z = 0.048z=0.048; expansion of the Universe
Redshift z=0.050z = 0.050z=0.050; expansion of the Solar System
53 exam-style questions on Edexcel GCSE Physics 7.2 The Universe and red-shift. Each one has a worked solution and a mark scheme showing where the marks go.