Which of the following is true about A-scans in phased array ultrasonic testing?

In phased array ultrasonic testing, A-scans are graphical representations that display the amplitude of ultrasonic echoes plotted against time. This means that the A-scan captures the strength of the reflected sound waves, providing insights into the characteristics of the material being inspected, such as the presence and size of flaws. By analyzing the amplitude over time, technicians can determine how deep a flaw might be and how reflective it is, which are critical factors in assessing material integrity.

The other options describe characteristics or functionalities that do not align with the purpose of A-scans. For example, while three-dimensional views of flaws can be obtained using other scanning methods or combined data (like B-scans or C-scans), A-scans themselves only provide a one-dimensional view of echo amplitude versus time. Similarly, A-scans do not directly represent the physical dimensions of the material; they measure echo characteristics rather than physical dimensions. Lastly, although the technology generally enhances inspection speed when used with phased array systems, the A-scan format itself is focused on amplitude and time, not speed. Thus, the nature of the A-scan specifically emphasizes amplitude over time, making "B" the correct choice.