Question

which type of wave has a disturbance that is only parallel to the wave motion?

○ transverse waves

○ transverse, longitudinal, and surface waves

○ surface waves

○ longitudinal waves

Explanation:

To solve this, we recall wave types:

• Transverse waves: Disturbance is perpendicular to wave motion (e.g., light, water ripples).
• Longitudinal waves: Disturbance is parallel to wave motion (e.g., sound waves, where particles oscillate back - and - forth along the wave's direction).
• Surface waves: Have a combination of transverse and longitudinal motions (occur at interfaces, like ocean waves).

So, only longitudinal waves have a disturbance parallel to wave motion.

Answer:

D. longitudinal waves (assuming the last option is D; if the options are labeled as: A. transverse waves, B. transverse, longitudinal, and surface waves, C. surface waves, D. longitudinal waves, then the answer is D. longitudinal waves)