Redshift from spectra
Redshift from spectra
When we observe a distant galaxy, we see light that left it long ago, so astronomy also lets us look back in time. The key evidence comes from absorption lines in a spectrum, because their laboratory wavelengths are known. If those lines are shifted to longer wavelengths, the galaxy is receding and the light is redshifted.
Step-by-step lessons covering Edexcel A Level Physics Age, fate and dark matter in the universe for A Level Physics. Each lesson works through exam-style questions in Paper 1, Paper 2 and Paper 3 format. Physics is one of the most mathematically demanding A Levels -- at least 40% of the marks across the three papers require maths skills at Level 2 (GCSE) standard or above, so build calculation and graph-handling fluency alongside the conceptual content from the start.
