In pulsed-wave transducers, the emitted frequency is inversely related to which property of the PZT?

In pulsed-wave transducers, the emitted frequency is inversely related to which property of the PZT?

• A. Temperature
• B. Transducer diameter
• C. PZT Thickness
• D. Electrical drive voltage

Answer: (C)

Pulsed-wave transducers emit at the resonant frequency of the piezoelectric element in its thickness mode. For a thin PZT plate, the fundamental resonance occurs when half a wavelength fits across the thickness, so the frequency is approximately f ≈ v_p / (2t), where v_p is the speed of sound in the PZT and t is the thickness. This makes the emitted frequency inversely related to the PZT’s thickness: a thinner element resonates at a higher frequency, while a thicker element resonates at a lower frequency. The transducer diameter mainly affects lateral modes and aperture, not the emission frequency; the electrical drive voltage affects amplitude, not frequency. Temperature can shift resonant conditions slightly but the direct, defining factor is the thickness of the PZT.

Pulsed-wave transducers emit at the resonant frequency of the piezoelectric element in its thickness mode. For a thin PZT plate, the fundamental resonance occurs when half a wavelength fits across the thickness, so the frequency is approximately f ≈ v_p / (2t), where v_p is the speed of sound in the PZT and t is the thickness. This makes the emitted frequency inversely related to the PZT’s thickness: a thinner element resonates at a higher frequency, while a thicker element resonates at a lower frequency. The transducer diameter mainly affects lateral modes and aperture, not the emission frequency; the electrical drive voltage affects amplitude, not frequency. Temperature can shift resonant conditions slightly but the direct, defining factor is the thickness of the PZT.