alleryStart learning →Sound waves in air are longitudinal. What does that say about the disturbance they carry?
AIt is parallel to the direction of propagation
BIt is at right angles to the propagation
CIt is a sideways shear of the air layers
DIt does not move in any fixed direction
Answer & Solution
Correct answer: A. It is parallel to the direction of propagation
1. A longitudinal wave, also called a compressional wave, disturbs the medium along the direction of travel.
2. For sound in air the disturbance is a periodic variation in pressure, pushing air back and forth along the path.
3. A disturbance at right angles to travel would make it transverse, which sound in air is not.
4. The alternating squeeze and stretch is what a sheet of paper picks up as a rattle in front of a speaker.
_Source: OpenStax College Physics (CC BY 4.0), Ch 16 "Oscillatory Motion and Waves", section Transverse and Longitudinal Waves_
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