When the waveforms are running,
a red crossed point will appear in the interference pattern. This is the observation
point, at where the two individual waveforms and the resultant waveform are
displayed on the right hand side of the applet.
The
observation point is draggable to move.
The
waveform of "wave I" is draggable to move up and down.
The grey lines of the interference pattern are the nodal
lines, at where the destructive interference takes place.
