Lots – hundreds at least – of small physics applets, around a wide range of topics, separated out into two semesters of college physics. Motion, thermo, EM, waves, and optics all covered. Created by Andrew Duffy.
Category: Optics
JavaLab
Just an amazing trove of science simulations built by middle school teacher, DJ Lee. I’m amazed at how much is covered here.
Index of Simulations
A spreadsheet pulled together for teachers of a categorized list of hundreds (wait, thousands!) of simulations you can find online, sorted by topic. An incredible resource organized by Helen Reynolds.
PhyPhox
Turn your phone into a physics lab. Graph things like acceleration, pressure, and magnetic field. Very powerful stuff. Created by RWTH Aachen University.
The Physics Classroom
Sets of pages with lessons and interactives about a variety of physics topics.
Sim Bucket
Various small simulations about chemistry and physics, created by Nerd Island Studios.
ScienceGameCenter
THE definitive list of science games – both digital and physical. Curated by Dr. Melanie Stegman.
Visualizing a Black Hole
Simulates the path of light around a black hole, and you can drag your view around. Created by Antonell.
MinuteLabs
A collection of science interactives by MinuteLabs.
PhET
The definitive collection of free online resources for physics classes. Run by University of Colorado Boulder.