Friday, 9 July 2021

Important_Question_of_Non-Destructive_Testing, #Ultrasonic_Testing (UT) Part-1 #NDT_Objective questions with answer key, #Ultrasonic_Testing (UT), # AKTU_NDT_exam #MCQ_Ultrasonic _testing_NDT

 

 ULTRASONIC TESTING (UT)

 Ultrasonic Testing Level 1 (UT-1) General Examination

Ultrasonic testing (UT) comprises a range of non-destructive testing (NDT) techniques that send ultrasonic waves through an object or material. These high frequency sound waves are transmitted into materials to characterise the material or for flaw detecting.



1. The divergence of an ultrasonic beam is dependant on:

(a) Transducer wavelength and diameter

(b) Test specimen density

(c) The sound wave's angle of incidence

(d) The degree of damping of the ultrasonic transducer

2. When a longitudinal wave is incident upon an inclined interface between zero degrees

and the first critical angle:

(a) The sound beam is totally reflected

(b) Only shear waves are produced in the second material

(c) Shear waves and longitudinal waves are produced in the second material

(d) Only longitudinal waves are produced in the second material

3. The piezoelectric material in a search unit which vibrates to produce ultrasonic waves

is called:

(a) A backing material

(b) A lucite wedge

(c) A transducer element or crystal

(d) A couplant

4. When a longitudinal wave is incident upon an inclined interface and is refracted at

ninety degrees, the angle of the incident longitudinal wave is called:

(a) The Snell constant

(b) The Snell angle

(c) The mode conversion constant

(d) The first critical angle

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5. When a longitudinal wave sound beam passes through an acoustic interface at some

angle other than zero degrees:

(a) Surface waves are generated

(b) Plate waves are generated

(c) Reflection, refraction and mode conversion will occur

(d) The first critical angle is reached

6. Which of the following can be a source of spurious ultrasonic signals?

(a) Surface roughness of the test piece

(b) Mode conversion within the test piece

(c) Shape or contour of the test piece

(d) All of the above

7. A noisy base line, or hash may result in:

(a) Laminations in the test piece

(b) Discontinuities at an angle to the test piece surface

(c) Large grain size

(d) Fatigue cracks

8. Sound waves which travel on the surface of a solid in a manner similar to waves on a

water surface are called:

(a) Rayleigh waves

(b) Shear waves

(c) Primary waves

(d) Compression waves

9. Lamb waves are formed in a part which has:

(a) A thickness greater that about ten wavelengths

(b) A thickness approximately equal to the wavelength

(c) Low acoustic impedance compared to the transducer crystal material

(d) A thickness of about four wavelengths

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10. Which type(s) of sound wave modes will propagate through liquids?

(a) Longitudinal

(b) Shear

(c) Surface

(d) All of the above

11. When the motion of the particles of a medium is transverse to the direction of

propagation, the wave being transmitted is called a:

(a) Longitudinal wave

(b) Shear wave

(c) Surface wave

(d) Lamb wave

12. Which of the following test frequencies would generally provide the best penetration

in a 12 inch thick specimen of coarse-grained steel?

(a) 1.0 MHz

(b) 2.25 MHz

(c) 5.0 MHz

(d) 10 MHz

13. An oscilloscope display in which the screen base line is adjusted to represent the one

way distance in a test piece is called a:

(a) A scan display

(b) B scan display

(c) C scan display

(d) D scan display

14. A common use of ultrasonic testing is:

(a) Cleaning

(b) Detecting of sub-surface indications

(c) Determination of the test piece ductility

(d) Communications

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15. Sound waves of a frequency beyond the hearing range of the human ear are referred

to as ultrasonic waves or vibrations, and the term embraces all vibrational waves of

frequency greater than approximately:

(a) 20 kHz

(b) 2 MHz

(c) 2 kHz

(d) 200 kHz

16. Y cut crystals produce:

(a) Longitudinal waves

(b) Shear waves

(c) Lamb waves

(d) Surface waves

17. The cable that connects the ultrasonic instrument to the search unit is specially

designed so that one conductor is centred inside another. The technical name for such

a cable is:

(a) BX cable

(b) Conduit

(c) Coaxial cable

(d) Ultrasonic conductor cable grade 20

18. As ultrasonic frequency increases:

(a) Wavelength increases

(b) Wavelength decreases

(c) Sound velocity increases

(d) Sound velocity decreases

19. In an A scan presentation, the amplitude of vertical indications on the screen

represents the:

(a) Amount of ultrasonic sound energy returning to the search unit

(b) Distance travelled by the search unit

(c) Thickness of material being tested

(d) Elapsed time since the ultrasonic pulse was generated

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20. Loss of the test piece back wall echo during scanning may be caused by:

(a) An abnormally homogeneous material structure

(b) A smooth entry surface on the test piece

(c) A discontinuity which is not parallel to the entry surface

(d) An opposite surface which is parallel to the entry surface

21. When a sound beam is reflected:

(a) The angle of reflection is found using Snell's law

(b) The angle of reflection equals the angle of incidence

(c) All the sound energy is reflected unless the acoustic impedance is zero

(d) Beam spread is decreased

22. Which of the following circuits converts electrical energy to ultrasonic energy?

(a) The pulse generator

(b) The transducer

(c) The transformer

(d) The power supply

23. An instrument display in which the horizontal base line represents elapsed time and

the vertical deflection represents signal amplitudes is called:

(a) A scan

(b) B scan

(c) C scan

(d) A time line display

24. Which of the following circuits provides short duration, high energy pulses which are

used to excite the transducer?

(a) The pulse generator

(b) The amplifier

(c) The transducer

(d) The clock

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25. A cross section view of a test piece is produced by which of the following?

(a) A scan

(b) B scan

(c) C scan

(d) A time line display

26. Echo amplitude losses may be caused by:

(a) Entry surface roughness

(b) Coarse grain size

(c) Discontinuity orientation

(d) All of the above

27. Which of the following is an advantage of using a focused transducer?

(a) The useful range of the transducer is decreased

(b) The useful range of the transducer is increased

(c) Sensitivity to the effects of a rough surface is increased

(d) Greater sensitivity is achieved in the transducer's useable range

28. Which of the following circuits provide current to operate the ultrasonic instrument?

(a) The pulse generator

(b) The amplifier

(c) The power supply

(d) The sweep generator

29. Which of the following is a true statement?

(a) Higher frequencies produce lower sensitivity

(b) Higher frequencies produce longer wavelengths

(c) Thicker crystals produce lower frequency transducers

(d) Longer wavelengths produce higher sensitivity

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30. Which type(s) of sound wave modes will propagate through solids?

(a) Longitudinal

(b) Shear

(c) Surface

(d) All of the above

31. The longitudinal wave incident angle at which the refracted shear wave angle equals

ninety degrees is called:

(a) The Snell angle

(b) The Snell constant

(c) The first critical angle

(d) The second critical angle

32. The amount of beam divergence from a crystal is primarily dependent on

the:

(a) Type of test

(b) Tightness of crystal backing in the search unit

(c) Frequency and crystal size

(d) Pulse length

33. In ultrasonic testing, a liquid coupling medium between the crystal surface and the

part surface is necessary because :

(a) Lubricant is required to minimize wear on the crystal surface

(b) An air interface between the crystal surface and the part surface would almost

completely reflect the ultrasonic vibrations

(c) The crystal will not vibrate if placed directly in contact with the surface of the

part being inspected

(d) The liquid is necessary to complete the electrical circuit in the search unit

34. X cut crystals produce:

(a) Longitudinal waves

(b) Shear waves

(c) Lamb waves

(d) Surface waves

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35. Lower frequency transducers are normally used:

(a) In contact testing applications

(b) In angle beam testing applications

(c) In immersion testing applications

(d) Where deeper penetration is required

36. All other factors being equal, which of the following modes of vibration has the

greatest velocity?

(a) Shear wave

(b) Transverse wave

(c) Surface wave

(d) Longitudinal wave

37. In immersion testing, the position of the search unit is often varied to transmit sound

into the test part at various angles to the front surface. Such a procedure is referred to

as:

(a) Angulation

(b) Dispersion

(c) Reflection testing

(d) Refraction

38. The angle of a refracted shear wave generated as a sound wave passes at an angle

through an acoustic interface is dependant on:

(a) The acoustic impedances of the materials of each side of the interface

(b) The frequency of the incident sound wave

(c) The wavelength of the incident sound wave

(d) The hardness of the materials on each side of the interface

39. Which of the following is a likely effect of a rough test piece surface?

(a) An improved ultrasonic signal to noise ratio

(b) A more penetrating sound beam

(c) Loss of discontinuity signal amplitude

(d) Higher test reliability

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40. Wavelength is:

(a) The distance from the crest to the next trough of a sound wave

(b) The time required for a sound wave to propagate from a trough to the next

trough of a sound wave

(c) The distance a sound wave travels in one second

(d) The distance from trough to trough or from peak to peak of a sound wave

41. The velocity of surface waves is approximately _______________ the velocity of

shear waves in the same material.

(a) Two times

(b) Four times

(c) One half

(d) Nine-tenths

42. An ultrasonic instrument control which allows moving an A scan display to the left or

right without changing the distance between any echoes displayed is called:

(a) The sweep length or range control

(b) The damping control

(c) The sweep delay

(d) The pulse length control

43. A disadvantage of using natural quartz crystals in a search unit is that:

(a) It will dissolve in water

(b) It is the least effective generator of ultrasonic energy of all commonly used

materials

(c) It easily loses it operating characteristics as it ages

(d) None of the above is correct

44. The formula Sin A/Sin B = VA/VB is known as:

(a) The Fresnell relationship

(b) Snell's law

(c) The law of sines

(d) The critical velocity ratio

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45. A 25 MHz search unit would most likely be used during:

(a) Straight beam contact testing

(b) Immersion testing

(c) Angle beam contact testing

(d) Surface wave contact testing

46. A technique in which two transducers are used, one on each side of the test piece, is

called:

(a) Angle beam testing

(b) Modified immersion testing

(c) Through transmission testing

(d) Twinning

47. Sound beam intensity is irregular in the area called:

(a) The near field

(b) The far field

(c) The beam spread

(d) The delay line

48. A more highly damped transducer crystal results in:

(a) Better resolution

(b) Better sensitivity

(c) Lower sensitivity

(d) Poorer resolution

49. The process of comparing an instrument or device with a standard is called:

(a) Angulation

(b) Calibration

(c) Attenuation

(d) Correlation

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50. Scattering of an ultrasonic beam is most pronounced when:

(a) Material grain size and wavelength are comparable

(b) Low frequency transducers are used

(c) Large wavelengths are used for ultrasonic testing

(d) None of the above

51. Ultrasonic testing is:

(a) Mechanical energy with a speed of propagation faster than the speed of sound

(b) Sound which has a frequency or pitch above the range of the human ear

(c) The science of discontinuity detection using ultrasonic sound

(d) Mechanical vibrations below the frequency of human hearing

52. Which technique would most likely be used to examine a weld, with the weld cap still

in place?

(a) Through transmission testing

(b) Angle beam testing

(c) Straight beam testing

(d) None of the above

53. The maximum frequency usually used for contact testing is:

(a) 1 MHz

(b) 5 MHz

(c) 10 MHz

(d) 25 MHz

54. Higher frequency transducers are normally used:

(a) In contact testing applications

(b) In angle beam testing applications

(c) In immersion testing applications

(d) Where deeper penetration is required

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55. Typical ultrasonic testing frequencies are:

(a) 50 kHz to 1 MHz

(b) 200 kHz to 25 MHz

(c) 10 MHz to 100 MHz

(d) 1 MHz to 5 MHz

56. ‘25 million cycles per second’ can also be stated as:

(a) 25 kHz

(b) 2500 kHz

(c) 25 MHz

(d) 25 Hz

57. A disadvantage of using a high frequency ultrasonic transducer is:

(a) It provides a smaller beam angle and better resolving power

(b) It provides a larger beam angle and poorer resolving power

(c) It is scattered more by coarse grained material

(d) It is scattered less by coarse grained material

58. Which of the following circuits provides timing signals to the pulser?

(a) The clock

(b) The amplifier

(c) The pulse generator

(d) The sweep generator

59. Which of the following search units would contain the thinnest quartz crystal?

(a) A 1 MHz search unit

(b) A 5 MHz search unit

(c) A 15 MHz search unit

(d) A 25 MHz search unit

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60. With longitudinal wave incident at angles between the first and second critical angles:

(a) The sound beam is totally reflected

(b) Only shear waves are produced in the second material

(c) Shear waves and longitudinal waves are produced in the second material

(d) Only longitudinal waves are produced in the second material

61. Sound velocity is described by which of the following relationships?

(a) Wavelength times frequency

(b) Wavelength divided by frequency

(c) Wavelength divided acoustic impedance

(d) Acoustic impedance divided by density

62. The relationship between the longitudinal wave incident angle and the refracted shear

wave angle is defined by:

(a) Snell's law

(b) Snell's constant

(c) The law of acoustics

(d) Fraunhofer’s law

63. Acoustic impedance is defined by which of the following relations?

(a) Material density/wavelength

(b) Material density × velocity

(c) Velocity/wavelength

(d) Velocity × wavelength

64. The upper limit of human hearing is normally considered to be about:

(a) 12 kHz

(b) 16 kHz

(c) 20 kHz

(d) 30 kHz

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65. Reference standards containing a series of flat bottom holes of the same diameter at

different depths in each block are called?

(a) Area-amplitude blocks

(b) Distance-amplitude blocks

(c) IIW blocks

(d) Sizing blocks

66. During ultrasonic testing by the immersion method, it is frequently necessary to

angulate the search unit when a discontinuity is located at an angle in order to:

(a) Avoid a large number of back reflections that could interfere with a normal test

pattern

(b) Obtain a maximum response if the discontinuity is not originally oriented

perpendicular to the ultrasonic beam

(c) Obtain a discontinuity indication of the same height as the indication from the

flat bottomed hole in a reference block

(d) Obtain the maximum number of entry surface reflections

67. Which of the following transducer materials is the most efficient receiver of

ultrasonic energy?

(a) Lead metaniobate

(b) Quartz

(c) Lithium sulphate

(d) Barium titanate

68. An ultrasonic wave in which particle displacement is 90 degrees to the direction of

wave propagation is called a:

(a) Longitudinal wave

(b) Shear wave

(c) Compressional wave

(d) Plate wave

69. An advantage of using lithium sulphate in search units it that:

(a) It is one of the most efficient generators of ultrasonic energy

(b) It is one of the most efficient receivers of ultrasonic energy

(c) It is insoluble

(d) It can withstand temperatures as high as 700ºC

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70. Moving a search unit over a test surface either manually or automatically is referred

to as:

(a) Scanning

(b) Attenuating

(c) Angulating

(d) Resonating




 

2 comments:

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    ReplyDelete