Using a pulse-echo technique, if the major plane of a flat discontinuity is oriented at some angle other than perpendicular to the direction of sound propagation, the results may be:

• A. Loss of signal linearity
• B. Loss or lack of a received discontinuity echo
• C. Focusing of the sound beam
• D. Loss of interference phenomena

Answer: (B)

In pulse-echo testing, you rely on energy that hits a flaw to bounce back toward the transducer so you can hear an echo. A flat discontinuity is like a mirror, reflecting sound at an angle equal to the incidence angle. If the major plane of that flat flaw is angled relative to the direction of the sound, the reflected energy is directed away from the transducer and the echo may not return. So you end up with a loss or absence of the received discontinuity echo. The other ideas aren’t about this reflection behavior: the flaw’s orientation doesn’t inherently cause signal linearity issues, beam focusing is determined by the probe geometry, and interference effects aren’t the primary outcome of an oblique flaw in pulse-echo.