Which term refers to the conversion of pressure to electric voltage?

• A. Piezoelectricity
• B. Capacitance
• C. Inductance
• D. Ohm's law

Answer: (A)

The conversion of pressure into an electrical signal in ultrasound comes from the piezoelectric effect. Certain crystals in the transducer, when subjected to mechanical stress from the sound wave, generate an electric voltage. This direct conversion underpins how the crystal receives echoes: tissue pressure from the returning ultrasound creates a voltage that the system processes. In transmit mode, applying voltage makes the crystal bend and emit sound, but the key concept here is the pressure-to-voltage conversion. Capacitance stores charge without converting pressure to voltage, inductance involves magnetic energy storage, and Ohm’s law describes a voltage–current–resistance relationship in circuits, not transduction of mechanical energy to electrical energy.