When the major plane of a flat discontinuity is tilted relative to the propagation direction, what is a common outcome in the received echo?

• 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)

When the major plane of a flat discontinuity is tilted, the reflection becomes directional and the energy no longer travels back to the probe. Ultrasonic reflections from flat surfaces follow the law of reflection: the echo returns most strongly when the plane is oriented so that the reflected ray comes back along the transducer’s path. Tilt the plane, and the reflected sound is directed away, so little or no energy returns to the receiver. That’s why the received discontinuity echo can be lost or greatly diminished. This effect isn’t about signal linearity, beam focusing, or interference phenomena—the key factor is the change in reflection direction due to the tilt.