With internal focusing, which component concentrates the sound energy into a narrower beam?

With internal focusing, which component concentrates the sound energy into a narrower beam?

• A. Flat piezoelectric crystal
• B. Curved piezoelectric crystal
• C. Lens
• D. Phased array

Answer: (B)

Internal focusing concentrates energy by shaping the emitting surface itself. A curved piezoelectric crystal acts like a concave lens for sound, so waves from different parts of the crystal reach a common focal point in phase. This makes the waves add up coherently at that depth, producing a narrower, more focused beam. If the crystal were flat, the beam would be broad and divergent. A lens would provide external focusing, not internal, and a phased array focuses by adjusting timing across many elements electronically rather than by the crystal’s shape alone.

Internal focusing concentrates energy by shaping the emitting surface itself. A curved piezoelectric crystal acts like a concave lens for sound, so waves from different parts of the crystal reach a common focal point in phase. This makes the waves add up coherently at that depth, producing a narrower, more focused beam.

If the crystal were flat, the beam would be broad and divergent. A lens would provide external focusing, not internal, and a phased array focuses by adjusting timing across many elements electronically rather than by the crystal’s shape alone.