Although it can be understood as such, Feynman does not say that two waves are out of phase only when the phase difference is $\pi$ (that is, 180 degrees). - Voltage waves 90° out of phase. In Phase and Out of Phase of Waves In Phase (+/+) Out of Phase (-/-) + and – are not charges they are amplitude of the wave Lets say I have a pos wave and andother + wave bc go in same direction combine and you create a larger pos wave that’s was a large bonding molec orbital looks like +-+- Wave phase is the offset of a wave from a given point. Out of phase waves f= 3;H* Frequency *L phase= 0; Plot@Sin@ 2p f t+ phaseD,8t,0,1