| There is a complicated interference pattern in the sound (or light)
produced by two similar point sources placed at a distance from each
other. There are lines of nodes where the two waves are anti-phase and
the interference is destructive, and there are lines of anti-nodes where
the interference is constructive. Because of this, the sound goes away
from these two sources along the directions of the lines of anti-nodes
while nothing goes away in the direction of the lines of nodes. Using
interference, one can build antennas emitting sound (or electromagnetic
radiation) in a desired direction. Move the slider to change the
distance between the sources. Wait for some time for the image to
rebuild because 2d calculations require a considerable computer
time. |