Which of the following is a common transducer type used in ultrasonic testing?

Contact transducers are a common choice in ultrasonic testing because they provide a direct interface with the material being tested. These transducers are designed to convert electrical energy into mechanical energy (ultrasound) and vice versa, allowing them to send and receive sound waves effectively. In ultrasonic testing, the sound waves are introduced into the material, and the reflections of these waves are analyzed to detect flaws or to determine the thickness of the material.

Contact transducers are particularly effective for applications where direct contact with the test material is feasible. They typically utilize a coupling medium, such as water or gel, to facilitate the transmission of sound waves and eliminate air gaps that would impede the ultrasound. This allows for accurate measurements and detection of defects.

The other types of transducers listed—capacitive, inductive, and resistive—are not standard in ultrasonic testing. Capacitive transducers are generally used in electric field applications rather than for sound wave transmission, inductive transducers are utilized in applications concerning magnetic fields, and resistive transducers are typically employed in temperature or pressure measurements. Therefore, contact transducers stand out as essential tools in the realm of ultrasonic testing.