What is a typical characteristic of an A-scan display?

An A-scan display is specifically designed to provide a graphical representation of time versus amplitude. In this format, the horizontal axis represents time, which indicates the travel time of sound waves as they move through a material, while the vertical axis represents the amplitude of the received signals. This allows operators to observe reflections from internal features and interfaces within the material being tested.

For example, when ultrasonic waves are transmitted into the material, echoes are generated when the waves hit boundaries or flaws, which are graphically represented as peaks on the display. This visual representation is critical for identifying the depth and size of imperfections and is a fundamental aspect of ultrasonic testing.

The other choices mention characteristics not typical of an A-scan display. While it does illustrate the amplitude of signals, it does not present them in a two-dimensional format, nor does it measure voltage signals directly; rather, it reflects how sound waves behave in the test material. A-scan displays are also not characterized by displaying continuous waveforms like those seen in other types of signals; they focus on distinct echo events at specific time intervals instead.