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When two e.m. waves 180deg out of phase 'cancel each other out', where does the energy go to ?
I'm thinking specifically about light or electromagnetic 'waves' here, but the same question could apply to sound, water etc. If energy cannot be destroyed, and yet the two waves appear to cancel and effectively disappear, where has the energy gone to ? Or do they not really cancel in the first place ?
2 Answers
- Anonymous1 decade agoFavorite Answer
What you have is two sets of potential energy in the two e.m. waves. What happens is the two potentials cancel each other out (if you had an electron there for the waves to act on the waves would exert opposite forces on the electron which net a force of zero).
So, the energy is still there... you just have two sets of opposite potential energy that would cancel each other out. It is kind of like being pushes equally from opposite directions. The energy is still there, it is just being canceled out by each other.
- mathematicianLv 71 decade ago
When destructive interference happens, there will always be someplace else where constructive interference happens. One aspect of this is that it is impossible to localize the energy of a wave. You can't say that the 'top of the wave' has a certain energy. It is the whole wave that has the energy. When waves interfer, there is just a redistribution of the energy into places where the waves add and away from where they cancel.
