Push-pull

Push-pull, said to be the relative state in which two waves whose difference in phase constants is equal to π + 2kπ radians (k = ±1,±2,...) are found.

In this way, when one reaches the maximum (absolute) displacement value, or what is the same, when it reaches its amplitude, the other also has a maximum amplitude, but in the opposite sign (although they are not the same in value). absolute). Another way to say it is that when one has phase |x| the other has phase -|x|.

Let's remember that being the formula of the displacement x of the wave movement:

x=A# (wt+d){displaystyle x=Acos(wt+d)}

the phase is (wt + d) and the phase constant is d.

When two waves of the same frequency enter a system out of phase, they interfere (either destructively or constructively, with which the resulting wave that finally enters the system may have a higher or lower amplitude than the waves it has received.

When two equal waves (in amplitude and frequency) enter a system at their moment of push-pull, they cancel.