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Interference
phenomenon in which two coherent waves combine into a resultant wave with greater intensity or lower amplitude / From Wikipedia, the free encyclopedia
In physics, interference is the effect of wave functions. A single wave can interfere with itself, but this is still an addition of two waves (see Young's slits experiment). Two waves always interfere, even if the result of the addition is complicated or not remarkable.
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Something that happens when two or more waves are in the same space. Sometimes the peak of one wave joins with the peak of another wave, so the resulting peak is twice as high. Sometimes the peak of one wave falls into the trough of another wave, and the surface is then flat. When waves add their effects, it is called positive interference, or constructive interference. When one wave subtracts from the effects of the other, it is called negative interference, or destructive interference.
If two people pushed on a car in the same direction, they would move the car better than either one alone. That would be positive interference. If two people of equal strength pushed the car from opposite directions, then it would not be moved by either of them. That would be negative interference.