What is an example of constructive interference?

Constructive interference occurs when two or more waves overlap in such a way that their individual displacements add together, resulting in a wave of greater amplitude than any of the individual waves. When two waves are in phase, meaning their peaks and troughs align, their amplitudes combine to create a stronger wave, which is the essence of constructive interference.

For example, if one wave has a peak at a certain point and another wave also has a peak at the same point, their amplitudes will sum at that location, leading to a wave that has a higher maximum displacement than either wave had individually.

In the provided alternatives, the scenario where two waves cancel each other out represents destructive interference, which is the opposite of constructive interference. Similarly, while waves reflecting off a surface and those traveling in opposite directions can interact in various ways, these scenarios do not necessarily lead to an increase in amplitude due to coherent overlap at a given point, which is required for constructive interference. Therefore, the situation that describes two waves resulting in a wave with a greater amplitude accurately exemplifies constructive interference.