試題詳解

45. A wave generated in a medium is a longitudinal wave when
(A) there is a net transport of matter by the wave.
(B) the molecules of the medium are unable to exert forces on each other.
(C) molecular displacements are parallel to the wave velocity.
(D) molecular displacements are perpendicular to the wave Velocity.
(E) the density of the medium is less than the density of matter.