Destructive interference
相消干涉

Destructive interference occurs when two sets of waves meet at positions where the waves arrive exactly out of phase; crests of a wave meet the troughs of the other and cancel each other.

In other words, destructive interference occurs at positions where the path difference is equal to 0.5λ, 1.5λ, 2.5λ, etc.

See also constructive interference.

Related topics:
10.2       Wave properties

Pronunciation in English (listen with default application).