These are an extensive set of interactive physics illustrations for use on a computer. They require Geometer's Sketchpad from Key Curriculum Press.

In these illustrations, the user can interactively change parameters and see the results. Sketches involving motion are also animated. The sketches show calculated results as well as changing diagrams as parameters change.

I have attempted to incorporate common sense limitations into the illustrations, e.g., the index of refraction of light is not less than one. Many sketches should be correct for subtle allowed situations such as putting the object behind the lens or obtaining the acceleration of gravity inside the earth.

The current set contains about fifty primary and over one hundred related secondary illustrations on a broad range of topics. They include:
Astronomy: solar system models, acceleration of gravity, force of gravity
Atomic: Bohr model: emission and absorption, energy levels, stimulated emission
Electrostatics: forces, field lines, equipotential lines
Magnetism: magnetic field near a straight wire, magnetic induction
Mechanics: kinematics, statics, Newton's second law, friction, energy, momentum
Thermodynamics: isotherms, isobaric expansion, isothermal expansion, adiabatic expansion, cyclic process
Modern:Millikan oil drop experiment
Geometric Optics:colors, refraction, dispersion, mirrors, lenses
Physical Optics: double slit, thin film
Optical Instruments: eye, magnifying glass, microscope, telescope
Waves: traveling, reflection, transmission, superposition, standing, resonance, beats, Doppler effect
Guided Activities:Projectiles, Kepler's Third Law, Refraction, Dispersion, Lenses, Waves