The Double Slit Wave-Particle JavaScript Model demonstrates how matter and light display both wave- and particle-like properties in single and double slit experiments.  The simulation shows a detector screen placed behind an aperture with one or two open slits.  Particles (electrons or photons) pass through the experiment one at a time and their impact is recorded on the screen.  Although it is at first difficult to discern a pattern, a diffraction (interference) pattern eventually emerges suggesting that each particle is interfering with itself.  The particle seems to be going through both slits as if it were a wave but is detected (observed) at only one location as if were a particle.  In other words, each particle is interfering with itself as if it were simultaneously passing through both slits.

The Double Slit Wave-Particle Duality JavaScript Model was developed using the Easy Java/JavaScript Simulations (EjsS) modeling tool. You can examine and modify this simulation if you have EjsS version 5.2 or above installed by importing the model's zip archive into EjsS.