What is the result when ultrasound waves encounter an interface with density differences?

What is the result when ultrasound waves encounter an interface with density differences?

• A. The waves change direction (refraction)
• B. The waves stop
• C. The waves gain mass
• D. The waves vanish

Answer: (A)

When ultrasound waves meet an interface where density changes, the speed of sound in the two media differs. This change in speed makes the wavefronts bend as the wave enters the new medium, so the transmitted beam changes direction. That bending is refraction. Some energy may reflect back at the boundary, but the key effect described here is the change in direction of the transmitted wave. The waves don’t stop, gain mass, or vanish simply because of a density difference.

When ultrasound waves meet an interface where density changes, the speed of sound in the two media differs. This change in speed makes the wavefronts bend as the wave enters the new medium, so the transmitted beam changes direction. That bending is refraction. Some energy may reflect back at the boundary, but the key effect described here is the change in direction of the transmitted wave. The waves don’t stop, gain mass, or vanish simply because of a density difference.