Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

30. On an A-scan display the dead zone refers to:
a. the distance contained within the near field (incorrect)
b. the area outside the beam spread
c. the distance covered by the front surface pulse width and recovery
time
d. the area between the near field and the far field
40. The second critical angle is the angle of the incident beam at which:
a. the angle of the refracted compression wave is 900
b. the angle of the reflected compression wave is 90°
c. total reflection occurs
d. surface waves are produced
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