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B Destructive interference

  1. Feb 27, 2017 #1
    This is a really silly question and its bugging me. Do I lose energy through destructive interference? If not... then how can I get back what I invested before?

    Thanks, hope I understand the waves soon :)
    Last edited: Feb 27, 2017
  2. jcsd
  3. Feb 27, 2017 #2


    Staff: Mentor

    Energy is conserved. In all experiences you'll have on this earth, you can bank on that certainty.

    However, the usefulness of energy in the forms you want it can easily be lost.

    You'll have to me more specific about what you're doing and whay you mean by getting it back for us to provide a better answer to your question.
  4. Feb 27, 2017 #3
    Well, getting it back in sense of absorbtion. Does the destructive interference simply penetrade matter?
  5. Feb 27, 2017 #4


    Staff: Mentor

    OK, consider sound waves, or light waves, or radio waves in air.

    Two sounds moving forward can interfere constructively at one point, then destructively further away, and constructively further on. The interference does not create or destroy energy. Ditto for radio or light.

    One or more waves hitting a surface can be absorbed or reflected, or any combination of absorption/reflection. The energy of absorbed waves turns into heat. The energy of reflected waves is carried away in the reflection. Interference between multiple waves doesn't change that.
  6. Feb 27, 2017 #5
    Thanks, makes asense
  7. Feb 27, 2017 #6


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    The energy has just been directed somewhere else, away from the nulls into the peaks of the interference pattern. You can 'get it back' when you find those peaks. If you ever go to the trouble of adding up the total energy in an interference pattern, you will get the same answer as adding the energy from both sources. (Personally, I accept that Energy is conserved)
  8. Mar 1, 2017 #7
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