The formula sinθ1 / V1 = sinθ2 / V2 is commonly referred to as

The formula sinθ1 / V1 = sinθ2 / V2 is commonly referred to as

• A. The acoustical impedance ratio formula
• B. The phase conversion formula
• C. The Fresnel zone formula
• D. Snell's law

Answer: (D)

The concept here is how a wave changes direction when it crosses an interface with a different propagation speed. For an ultrasonic wave moving from a medium with velocity V1 to one with velocity V2, the angles of incidence and transmission are tied together by a form of Snell's law: sinθ1 / V1 = sinθ2 / V2. This comes from the need for the wave's phase to match along the boundary, which gives k1 sinθ1 = k2 sinθ2, with k = ω/V. Since the frequency ω is the same on both sides, dividing by ω yields the velocity form of Snell's law. It explains why the beam bends toward or away from the normal depending on whether V2 is smaller or larger than V1, which is crucial for predicting the beam path in ultrasonic testing. The other options refer to different concepts (impedance-related reflections, phase conversion, or Fresnel zones) and do not describe the refraction of a wave at an interface, making Snell's law the correct description for this relationship.

The concept here is how a wave changes direction when it crosses an interface with a different propagation speed. For an ultrasonic wave moving from a medium with velocity V1 to one with velocity V2, the angles of incidence and transmission are tied together by a form of Snell's law: sinθ1 / V1 = sinθ2 / V2. This comes from the need for the wave's phase to match along the boundary, which gives k1 sinθ1 = k2 sinθ2, with k = ω/V. Since the frequency ω is the same on both sides, dividing by ω yields the velocity form of Snell's law. It explains why the beam bends toward or away from the normal depending on whether V2 is smaller or larger than V1, which is crucial for predicting the beam path in ultrasonic testing. The other options refer to different concepts (impedance-related reflections, phase conversion, or Fresnel zones) and do not describe the refraction of a wave at an interface, making Snell's law the correct description for this relationship.