Interference

The combining of two or more signals (superposition of waves) results in an interaction called interference. This may be constructive or destructive. Another use of the term is to refer to undesired signals, such as noise on a radio transmission.

Constructive Interference

When the peaks and troughs of two interfering waves match, the amplitudes add to give the resultant wave a higher amplitude.

Destructive Interference

When the peaks of one wave match the troughs of another, the waves interfere destructively. The amplitudes of the interfering waves cancel to give the resultant wave a lower amplitude.

See also: Optical Interference.