Name the three primary UT display formats and a key use for each.

• A. A-scan: 2D cross-section image; B-scan: depth sizing; C-scan: plan view of reflectivity.
• B. A-scan: time/amplitude for depth sizing; B-scan: 2D cross-section image; C-scan: plan view of reflectivity.
• C. A-scan: plan view of reflectivity; B-scan: time/amplitude; C-scan: 3D image.
• D. A-scan: depth profiling; B-scan: surface profile; C-scan: color map of composition.

Answer: (B)

Understanding UT display formats helps you interpret what you’re seeing during an inspection. An A-scan is a time-domain trace that plots signal amplitude versus time (or depth, after converting with the material’s velocity). It’s used for depth sizing because you measure how long it takes for echoes to return from a reflector and translate that into distance. A B-scan builds on those traces by stacking them along the scan path to produce a two-dimensional image, giving a cross-sectional view with depth on one axis and horizontal position on the other. A C-scan maps reflectivity across a plane at a fixed depth, providing a plan view of the inspected area to show where features or defects occur over the surface.

So the described set—A-scan as time/amplitude for depth sizing, B-scan as a 2D cross-section image, and C-scan as a plan view of reflectivity—matches how these displays are typically used in UT. The other interpretations mix up the roles (for example, A-scan is not a 2D cross-section, and C-scan is not a 3D image or a color map of composition).