If the angle between the ultrasound pulse and the boundary is 90 degrees, this incidence is called?

If the angle between the ultrasound pulse and the boundary is 90 degrees, this incidence is called?

• A. Direct incidence
• B. Oblique incidence
• C. Indirect incidence
• D. Orthogonal incidence

Answer: (D)

When the ultrasound beam meets a boundary at a right angle to the surface, the beam is perpendicular to the interface. This is described as orthogonal incidence. At this orientation there is no bending of the transmitted wave (no refraction) because the angle relative to the boundary’s normal is zero, so the ray travels straight into the second medium. The reflection that does occur depends mainly on the difference in acoustic impedance between the two media. Other terms like direct or indirect incidence aren’t standard in this context, and oblique incidence would mean the beam hits the boundary at some angle other than 90°, which would involve refraction and a change in the transmitted direction.

When the ultrasound beam meets a boundary at a right angle to the surface, the beam is perpendicular to the interface. This is described as orthogonal incidence. At this orientation there is no bending of the transmitted wave (no refraction) because the angle relative to the boundary’s normal is zero, so the ray travels straight into the second medium. The reflection that does occur depends mainly on the difference in acoustic impedance between the two media.

Other terms like direct or indirect incidence aren’t standard in this context, and oblique incidence would mean the beam hits the boundary at some angle other than 90°, which would involve refraction and a change in the transmitted direction.