A short burst of alternating electrical energy is called:

• A. A pulse
• B. A continuous wave
• C. An ultrasonic wave
• D. A peaked DC voltage

Answer: (A)

That phrase describes a pulse. In ultrasonic testing, a short burst of alternating electrical energy is used to excite the transducer, producing a brief ultrasonic pulse. The key is the finite duration—the signal starts and stops—so you can listen for echoes after the burst to determine depth and locate flaws. A continuous wave is an ongoing oscillation with no distinct start or end, which makes it hard to separate emitted energy from echoes. An ultrasonic wave refers to the actual sound wave in the material, not the electrical drive. A peaked DC voltage isn’t alternating energy, and it doesn’t create the short, transient burst used for pulsed ultrasonic testing.