Why does a wave reflect on the edge of an open tube? There is nothing solid to make the wave bounce.

Then why is it reflected?


1 Answer 1


The boundary condition is that the sound pressure is zero there.

  • $\begingroup$ Is pressure zero? what do you mean... $\endgroup$
    – molo32
    Sep 15, 2019 at 18:48
  • $\begingroup$ The pressure there is given by the ambient pressure (for example 1 atm). This gives that the sound pressure is (almost) zero there, much smaller than inside the tube. So for the sound pressure, this is a fixed end. $\endgroup$
    – user137289
    Sep 15, 2019 at 18:57
  • $\begingroup$ @Pieter The pressure variation about atmospheric pressure is zero. $\endgroup$
    – Farcher
    Sep 15, 2019 at 19:21

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