This app allows you to explore the origins and properties of two-source interference. Click the arrow at the bottom left to start the animation. The red semicircles represent wave crests and the blue ones wave troughs. Use the checkboxes to turn off the display of wavefronts (which are pretty but distracting) and turn on tools that allow you to explore the superposition of the two waves at various points on a screen. Displays show the instantaneous wave amplitude, average wave intensity, and phase difference between the two interfering waves. Drag the point to trace out the intensity distribution. Use the sliders in the upper left to adjust the source separation and wavelength.
Roger Tobin, Created with GeoGebra