In the context of waves, what is "constructive interference"?

Constructive interference occurs when two or more waves meet and combine in such a way that their amplitudes add together, resulting in a wave that has a greater amplitude than either of the individual waves. This phenomenon typically happens when the waves are in phase, meaning that the crests of one wave align with the crests of another wave, and the troughs align as well. As a result, the overall effect is an amplification of the wave's characteristics, leading to a larger maximum displacement.

In contrast, the other scenarios described do not represent constructive interference. For example, when waves combine to reduce amplitude, it indicates destructive interference where the waves are out of phase, leading to cancellation effects. Waves that cancel each other out demonstrate this principle further. Waves becoming stationary implies a lack of movement or propagation, which is not related to the interaction of amplitudes. Therefore, the correct understanding of constructive interference highlights the amplification of waves when they interact positively.