Questions With Verified Answers
\.1. The indication on the instrument display that represents the far boundary of material being
tested is called: - Answer- the back-surface reflection.
\.2. In immersion testing, the position of the transducer is often varied by a manipulator to
transmit sound into the test part at various angles to the front surface. Such a procedure is
referred to as: - Answer- angulation.
\.3. The technical name for the cable that connects the ultrasonic instrument to the transducer
is: - Answer- coaxial cable
\.4. The process of standardizing an instrument or device by using a reference standard is called:
- Answer- calibration.
\.5. Another name for a compressional wave is: - Answer- longitudinal wave.
\.6. Another name for rayleigh waves is : - Answer- surface waves.
\.7. A material used between the face of a transducer and the test surface to permit or improve
the transmission of ultrasonic vibrations from the transducer to the material being tested is
called: - Answer- a couplant.
\.8. The piezoelectric material in a transducer that vibrates to produce ultrasonic waves is called
a - Answer- crystal.
,\.9. Ultrasonic testing of material where the probe is in direct contact with the material being
tested may be: - Answer- straight beam testing.
\.10. An advantage of using lithium sulfate in transducers is that it: - Answer- is one of the
most efficient receivers of ultrasonic energy
\.12. The transducer that contains the thinnest piezoelectric crystal is a: - Answer- 25 MHz
transducer
\.13. Penetration of ultrasonic waves in a material is normally the function of test frequency
used. The greatest depth of penetration is provided by a frequency of - Answer- 1 MHz
\.14. The amount of beam divergence from a crystal is primarily dependent on the - Answer-
frequency and crystal size.
\.15. When an ultrasonic beam passes through the interface between two dissimilar materials
at an angle, a new angle of sound travel takes place in the second material due to: - Answer-
refraction.
\.21. The velocity of longitudinal waves is approximately __________ the velocity of shear
waves in the same material. - Answer- two times
\.27. Under most circumstances, which of the following frequencies would result in the best
resolving power? - Answer- 25 MHz
\.28. Which of the following materials of the same alloy is most like ly to produce the greatest
amount of sound attenuation over a given distance? - Answer- A coarse-grained casting.
, \.29. In contact testing, the entry surface indication is sometimes referred to as the: - Answer-
initial pulse.
\.30. An ultrasonic instrument display pattern containing a large number of low-level indications
(often referred to as grass or hash) could be caused by: - Answer- coarse-grained material.
\.31. A test method employing two separate transducers on opposite surfaces of the material
being tested is called - Answer- through-transmission testing
\.32. The number of complete waves that pass a given point in a given period of time (usually 1
s) is referred to as the - Answer- frequency
\.33. The boundary between two different materials that are in contact with each other is
called: - Answer- an interface.
\.34. When the motion of the particles of a medium is transverse to the direction of
propagation, the wave being transmitted is called a: - Answer- longitudinal wave.
\.36. The "25 milion eycles per second" can be stated number as: - Answer- 25 MHz.
\.37. Moving a transducer over a test surface either manually or automatically is referred to as: -
Answer- scanning.
\.38. A term sound waves pass through various substances is: used in ultrasonics to express the
rate at which - Answer- velocity