This program simulates wave interference from two point sources, or from monochromatic light through a double slit as demonstrated by Thomas Young in 1801. The sliders at the bottom allow you to adjust the wavelength and slit spacing to see the effect on the interference pattern. Set "show lines" to 1 to highlight the lines of constructive interference. Version 2 adds animation of propagating waves!
This is my first Scratch project! It uses all of my own code, though I had to look around to find out how to draw a circle with the pen. I then generalized that method into a block of my own called "circle", which allows you to specify a diameter, center location, color, and arc length - I figured that this is code I might be able to re-use some day. I tried to locate the locate the arc intersections using the "touching color" functionality, but didn't have much luck. So I ended up calculating the points independent of the arc drawing by using Heron's formula.
