Keyboard: focus the canvas with Tab, then use the arrow keys to move the probe.How to use: Drag the white probe anywhere on the ripple field.
Below, you'll see the wave arriving from source A, the wave arriving from
source B, and what you actually get where they meet.
Try dragging the probe onto a bright band — then onto a dark band.
Watch the bottom trace change shape.
Notice: where the two waves arrive in step, they add up to a wave twice as tall (bright band). Where they arrive out of step, they cancel to nothing (dark band). Same sources, same waves — only the position changed.