Unlike a transverse wave, the disturbance in a longitudinal wave is

parallel to the wave motion

perpendicular to the wave motion

in a circular motion

in the opposite direction of the wave motion

Parallel to the wave motion

Explanation:

Longitudinal waves are waves that propagates in the direction of the wave motion.

Transverse waves are perpendicular.

Parallel to the wave motion

Explanation:

The waves that requires a medium to travel are called mechanical wave. There are two types of mechanical wave i. e.

(1) Longitudinal wave

(2) Transverse wave

The longitudinal wave travel in the form of compression and rarefaction. In this type, the displacement of medium is in same direction to the direction of propagation of wave. In case of transverse wave, the oscillation of particle is in perpendicular direction.

Hence, the correct option for longitudinal wave is " parallel to the wave motion ".