Interference (Encyclopedia of Science)
Interference is the interaction of two or more waves. Wave motion is a common phenomenon in everyday life. Light and sound, for example, are transmitted by waves. In addition, waves can often be seen on lakes, ponds, and other bodies of water.
All waves have high points, called crests, and low points, called troughs (pronounced trawfs). Suppose that two or more waves are generated at the same time, as shown in the accompanying photograph. Here, water waves are spreading out from the point where pebbles have been dropped into a pond. You can see how the waves overlap each other at various points on the surface of the water. This overlapping effect is interference.
Constructive and destructive interference
In general, waves can interfere with each other in one of two ways: constructively or destructively. When the crests of two waves and the troughs of two waves arrive at a given spot at the same time, their effects are added to each other. The result is constructive interference. When the crest of one wave and the trough of a second wave arrive at the same time, their effects cancel each other out. The result is destructive interference.
Interference of sound waves. Constructive and destructive interference can be detected by the intensity of the result. For example, suppose that two sound waves interfere with each...
(The entire section is 526 words.)
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Interference (West's Encyclopedia of American Law)
In the law of PATENTS, the presence of two pending applications, or an existing patent and a pending application that encompass an identical invention or discovery.
When interference exists, the PATENT AND TRADEMARK OFFICE conducts an investigation to ascertain the priority of invention between the conflicting applications, or the application and the patent. A patent is customarily granted to the earlier invention.
(The entire section is 62 words.)