5.31. Wave Interference http://www.ck12.org
FIGURE 5.64
Standing Waves
Waves may reflect off an obstacle that they are unable to pass through. When waves are reflected straight back
from an obstacle, the reflected waves interfere with the original waves and createstanding waves. These are waves
that appear to be standing still. Standing waves occur because of a combination of constructive and destructive
interference. You can see animations of standing waves at the URLs below.
- http://skullsinthestars.com/2008/05/04/classic-science-paper-otto-wieners-experiment-1890/
- http://www.physicsclassroom.com/mmedia/waves/swf.cfm
Q: How could you use a rope to produce standing waves?
A: You could tie one end of the rope to a fixed object, such as doorknob, and move the other end up and down to
generate waves in the rope. When the waves reach the fixed object, they are reflected back. The original waves and
the reflected waves interfere to produce a standing wave. Try it yourself and see if the waves appear to stand still.
Summary
- Wave interference is the interaction of waves with other waves.
- Constructive interference occurs when the crests of one wave overlap the crests of the other wave, causing an
increase in wave amplitude. - Destructive interference occurs when the crests of one wave overlap the troughs of the other wave, causing a
decrease in wave amplitude.