http://www.ck12.org Chapter 5. Energy
5.31 Wave Interference
- Define wave interference.
- Compare and contrast constructive and destructive interference.
- Explain how standing waves occur.
When raindrops fall into still water, they create tiny waves that spread out in all directions away from the drops.
What happens when the waves from two different raindrops meet? They interfere with each other.
When Waves Meet
When two or more waves meet, they interact with each other. The interaction of waves with other waves is called
wave interference. Wave interference may occur when two waves that are traveling in opposite directions meet.
The two waves pass through each other, and this affects their amplitude. Amplitude is the maximum distance the
particles of the medium move from their resting positions when a wave passes through. How amplitude is affected
by wave interference depends on the type of interference. Interference can be constructive or destructive.
Constructive Interference
Constructive interference occurs when the crests, or highest points, of one wave overlap the crests of the other wave.
You can see this in theFigure5.64. As the waves pass through each other, the crests combine to produce a wave
with greater amplitude. You can see an animation of constructive interference at this URL: http://phys23p.sl.psu.ed
u/phys_anim/waves/embederQ1.20100.html
Destructive Interference
Destructive interference occurs when the crests of one wave overlap the troughs, or lowest points, of another wave.
TheFigure5.65 shows what happens. As the waves pass through each other, the crests and troughs cancel each
other out to produce a wave with zero amplitude. You can see an animation of destructive interference at this URL:
http://phys23p.sl.psu.edu/phys_anim/waves/embederQ1.20200.html