If the direction of the vibration of particles is parallel to the

SOLUTION

Concept:

Longitudinal waves are the waves in which the particle of the medium vibrates parallel to the direction of its propagation.

Sound waves are the best example of longitudinal waves.

This diagram shows how longitudinal (sound) waves are propagated in a medium.

Here dots represent air molecules and more dots at some area represents a region of compression or increased pressure whereas fewer dots at the same area represents the region of rarification or decreased pressure.

Transverse waves are the waves in which the particle of the medium vibrates perpendicular to the direction of its propagation.

Water ripple is an example of a transverse wave in which water molecules vibrates perpendicular to the surface of the water while the wave propagates along the surface.

In a transverse waves particle of the medium vibrate up and down in the vertical direction whereas it is propagating along the horizontal direction.

Hence in a transverse wave, a crest is a part where particle rise from its mean position whereas trough is a part where particle dips below mean position.

Explanation:

Longitudinal waves are waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of propagation of the wave.