Constructive and destructive interference of sine functions

Author:
David Wees
This diagram shows two sine functions being added together along with two sliders that allow the wavelength of those sine functions to be controlled. The idea is to show that with different ratios of a and b the two sine functions show more or less areas of constructive version destructive interference.
Try different values of a and b. See what happens if you choose a and b such that a/b is a nice whole number.