The line on the diagram which indicates one wavelength of the wave is:
- The arrow below the top one
According to the given question, we are asked to show the line on the diagram which indicates one wavelength of the wave and jow it propagates and what effect it has.
As a result of this, we can see that there are longitudinal waves which are in motion, propagating from left to the right and the line which shows one wavelength of the wave is the rarefaction point where the ovals in the diagram spread themselves.
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https://brainly.com/question/9510931