# Wave Interference

Anyone who as watched the surface of a swimming pool has observed wave* interference. Wave interference occurs when two or more waves move through the same space at the same time. Unlike solid matter, waves move through each other. The principle of superposition describes the response of a medium being displaced by more than one wave.

Forward Wave:
Wavelength*:
Waveheight:
Reverse Wave:
Wavelength:
Waveheight:
Graphing:

Observer Position: 0 m

Physical wave*s are energy moving through a medium. This energy [link]displaces particles from their resting position[/link]. With two or more waves, the total displacement equals the sum of the displacement caused by the individual wave.

Depending upon the orientation of the peaks and troughs of each wave, superposition can result in a combined wave that is either larger or small than the contributing waves.

When the peaks line up with peaks and troughs with troughs, the peaks and troughs of the combined waves will be larger than those of the individual waves. This is constructive interference. The opposite of constructive interference is destructive interference. Destructive interference occurs when the peaks of one wave line up with the troughs of another.

Superposition only lasts as long as the two waves are in the same space. If waves moving in different directions meet, they interact while they are in the same space. Then, once they have moved past each other, each regains its original size and continues on as if the interaction had never occurred.

The principle of wave superposition applies to interactions between two OR MORE waves, but the concept is easiest to illustrate with two waves.

The illustration above explores constructive and destructive wave interference between two waves moving in opposite directions. A video demonstration of the illustration can be found below the illustration.You can also test your understanding with the wave interference concept questions.

Demonstration Video
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