Where is the point of maximum intensity in a sound beam?

• A. A curie point
• B. B fresnel zone
• C. C focal point
• D. D fraunhofer zone

Answer: (C)

Focusing concentrates energy into a small spot, so the point where the waves meet in phase—the focal point—has the highest intensity. The transducer’s curved aperture or lens directs the waves to converge there, creating the greatest pressure amplitude in the smallest area. Before and after this focus, the beam spreads and the intensity drops. The near-field Fresnel zone shows complex, nonuniform patterns, while the far-field Fraunhofer zone is where the beam has spread out and is less intense. The Curie point is unrelated in this context; it’s the temperature at which piezoelectric materials lose polarization, not where the beam’s intensity peaks.