Reading the H-R diagram
Reading the H-R diagram

An H-R diagram plots stars by luminosity and surface temperature. Luminosity is a star's true power output, measured in watts, so it avoids the distance problem that affects apparent brightness.
Step-by-step lessons covering Edexcel A Level Physics Hertzsprung-Russell diagrams and stellar evolution 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.