Comprehensive and clearly structured notes for OCR A A-Level Physics – Module 4: Electrons, Waves and Photons. This document focuses on key derivations, equations, and core concepts required for exams, making it ideal for revision and understanding how formulas are developed.



The notes include step-by-step derivations and explanations for:



Electron drift velocity (I = nAve)

Potential divider equations

Electrical power equations (P = IV, P = I²R, P = V²/R)

Resistors in series and par...