Lens basics
Lens basics

A lens changes the direction of light by refraction as light passes between materials where it travels at different speeds. In the thin lens approximation, we treat the bending as if it happens at one vertical line through the optical centre.
Step-by-step lessons on Edexcel A Level Physics Lenses and optical images. Each one builds up to exam-style questions. 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.