Below are links to various on-line resources discussing wave interference, principally applets, with some notes about what each shows.

applet showing superposition of various simple pulse shapes

applet showing superposition of various sinusoidal waves

Intereference of two sources Note that you can move one or both sources by clicking and dragging. Constructive interference occurs where two lines cross each other (two crests at same place at same time).

Check your understanding of constructive and destructive interference The exercise of interest is at the bottom of the lesson.

A pausable, 2D visualization of wave intereference

This is a very close-up view of an interference pattern. It's a scenario like the example in Young and Freedman chapter 16.

Waves from a variety of sources including ones that show interference