Free physics notes
Physics, explained chapter by chapter
Notes that cover the concepts, work through the derivations, and show the results — with diagrams, typeset equations, and simulations you can try yourself.
“The whole of science is nothing more than a refinement of everyday thinking.”
Albert Einstein1879–1955 · RelativityPhysics and Reality, 1936
Photograph by Ferdinand Schmutzer, 1921. Public domain.
Curriculum
The six branches of physics
Each branch is divided into chapters meant to be read in order, since later chapters build on earlier ones. Mechanics is available now; the remaining branches are in progress.
- 01
Mechanics
Kinematics, Newton’s laws, work and energy, momentum, rotation, and gravitation.
- 02
Waves & Oscillations
Simple harmonic motion, damping and resonance, sound, standing waves, and interference.
- 03
Thermodynamics
Temperature, heat transfer, kinetic theory, the laws of thermodynamics, and entropy.
- 04
Optics
Reflection and refraction, mirrors and lenses, diffraction, and polarization.
- 05
Electrodynamics
Electric and magnetic fields, circuits, induction, and Maxwell’s equations.
- 06
Modern Physics
Special relativity, quanta, atomic structure, nuclei, and particles.
Inside a chapter
What every chapter includes
Step-by-step derivations
Every result is derived from stated assumptions, so you can follow each step instead of taking it on trust.
Clearly typeset equations
Math is typeset with KaTeX, so it stays sharp, selectable, and readable at any size.
Diagrams and video
Labelled figures for the geometry, plus a video explanation where watching is easier than reading.
Interactive simulations
Simulations sit next to the theory, so you can change one variable and see how the rest responds.