WAEC Physics 2012 Theory — Question 5

Model answer

Sound waves are longitudinal waves — the particles of the medium vibrate parallel to (along) the direction of wave propagation, not perpendicular to it. Polarization involves restricting vibrations to a single plane perpendicular to the direction of travel, which is only possible for transverse waves (where vibrations are already perpendicular to the direction of travel, in multiple possible planes). Since sound wave vibrations only occur along one direction (the direction of propagation) to begin with, there is no additional plane to restrict, so sound waves cannot be polarized.