In a longitudinal ultrasound wave, particle displacement is what relative to the direction of travel?

In a longitudinal ultrasound wave, particle displacement is what relative to the direction of travel?

• A. Parallel to direction of ultrasound
• B. Perpendicular to direction of ultrasound
• C. Circular
• D. Random

Answer: (A)

In a longitudinal ultrasound wave, the particles in the medium vibrate along the same line as the wave is traveling. This back-and-forth motion creates zones of compression and rarefaction as the pressure disturbance moves forward. If the particle motion were perpendicular to the travel direction, it would be a transverse wave; circular or random motion doesn’t describe the organized, in-line displacement of a longitudinal wave. So the displacement is parallel to the direction of travel.

In a longitudinal ultrasound wave, the particles in the medium vibrate along the same line as the wave is traveling. This back-and-forth motion creates zones of compression and rarefaction as the pressure disturbance moves forward. If the particle motion were perpendicular to the travel direction, it would be a transverse wave; circular or random motion doesn’t describe the organized, in-line displacement of a longitudinal wave. So the displacement is parallel to the direction of travel.