Snell's Law describes:

Snell's Law describes:

• A. The angle of sound transmission at an interface between media having different propagation speeds.
• B. The percentage of reflection at an interface with normal incidence and different densities.
• C. The amount of attenuation of sound tissue with depth.
• D. The angle of sound reflection at an interface with oblique incidence and nonspecular reflection.

Answer: (A)

Snell's law describes how a wave changes direction when it passes from one medium to another with a different propagation speed. For sound, speeds differ between the two media, so the incident angle and the transmitted angle are linked by sin θ1 / c1 = sin θ2 / c2 (equivalently c1 sin θ1 = c2 sin θ2). This explains refraction: if the second medium is faster, the transmitted ray bends away from the normal; if slower, it bends toward the normal. It does not specify how much energy is reflected at the boundary—that depends on impedance—nor does it describe attenuation with depth or the angle of reflection, which is governed by the law of reflection. Thus, the description matches the concept of the angle of transmission at an interface with differing speeds.

Snell's law describes how a wave changes direction when it passes from one medium to another with a different propagation speed. For sound, speeds differ between the two media, so the incident angle and the transmitted angle are linked by sin θ1 / c1 = sin θ2 / c2 (equivalently c1 sin θ1 = c2 sin θ2). This explains refraction: if the second medium is faster, the transmitted ray bends away from the normal; if slower, it bends toward the normal. It does not specify how much energy is reflected at the boundary—that depends on impedance—nor does it describe attenuation with depth or the angle of reflection, which is governed by the law of reflection. Thus, the description matches the concept of the angle of transmission at an interface with differing speeds.