In standing sound wave in a pipe, nodes are regions of…?

Question

a- maximum or minimum pressure and low displacement

b- maximum or minimum pressure and high displacement

c- mean atmospheric pressure and low displacement

d- mean atmospheric pressure and high displacement

Answer 1

By definition, a node is where things aren't oscillating around the mean, and antinodes are where they oscillate the most.

However, a sound wave has variation in both displacement and pressure.  A sound node is where the displacement is the least, while areas to either side of it compress and rarify...in other words, the pressure can change while the molecule stands still and its neighbors move around.