What features of longitudinal waves take the place of crests and roughs found in transverse waves?

1 Answer
Jun 21, 2014

Compressions and rarefactions.

At a compression the local pressure is increased and particle vibration is restricted

At a rarefaction the local pressure is reduced and particle vibration is increased.

I don't think there is a strict convention on translating peaks and troughs to compressions and rarefactions when representing longitudinal waves with a transverse graphic but perhaps the following method will make sense to you. Peaks and troughs could represent the local pressure. So a peak would represent a compression and a trough would represent a rarefaction.