What you’ll learn4 learning objectivesChoose one objective for a focused lesson, or study the complete topic.25.3.1The lines in the emission and absorption spectra• understand that the lines in the emission and absorption spectra from distant objects show an increase in wavelength from their known valuesSyllabus objective25.3.2Redshift of electromagnetic radiation• use ∆λ / λ ≈ ∆f / f ≈ v / c for the redshift of electromagnetic radiation from a source moving relative to an observerSyllabus objective25.3.3Why redshift leads to the idea that the universe is expanding• explain why redshift leads to the idea that the universe is expandingSyllabus objective25.3.4Hubble’s law v ≈ H0d and explain how this leads to the Big Bang theory• recall and use Hubble’s law v ≈ H0d and explain how this leads to the Big Bang theory (candidates will only be required to use SI units)Syllabus objective