Quiznetik

Non Destructive Testing and Evaluation | Set 8

1. A good Cobalt-60 shot is made on a 7.6 cm (3 inches) steel casting using an exposure time of 10 minutes and a source-to-film distance of 91.5 (36 inches). If it is necessary to change the source-to-film distance to 61 cm (24 inches), what exposure time would produce a similar radiograph if all other conditions remain the same?

Correct : B. 4.4 minutes

2. A radiographic exposure with 3700 GBq (100 Ci) source of Ir-192 using source to film distance of 60 cm results in a radiation intensity of 0.12 Gy/h (11.8 R/h) and a radiographic density of 2.5. The intensity of radiation needed to obtain the same density when the source to film distance is changed to120 cm is:

Correct : C. 0.029 Gy/h (2.9 R/h)

3. A 7.6 cm (3 inches) thick test specimen is radiographed with a source having size of 1.3 cm (1/2 inch), the film is placed in contact with the test specimen. The source to film distance is 40.6 cm (16 inches).The geometric unsharpness obtained is:

Correct : B. 0.3 cm

4. Radiographic equivalence factors for Inconel and 304 stainless steel are 1.4 and 1.0 respectively. What is the approximate equivalent thickness of Inconel requiring the same exposure as 1.27 cm (½ inch) thickness of 304 stainless steel?

Correct : C. 0.9 cm (0.36 inches)

5. The approximate radiographic equivalence factors for steel and copper at 220 kV are 1.0 and 1.4 respectively. If it is desirable to radiograph a 1.27 cm (0.5 inch) piece of copper, what thickness of steel would require about the same exposure characteristics?

Correct : A. 1.78 cm (0.7 inches)

6. If an exposure time of 60 seconds and source to film distance of 365.7 m (1200 feet) is necessary for a particular exposure, what exposure time would be needed for an equivalent exposure if the source- to-film distance is changed to 457.2 m (1500 feet)?

Correct : B. 94 seconds

7. Subject contrast and film contrast are the two factors that comprise radiographic:

Correct : C. Contrast

8. ‘Film contrast’ is the inherent ability of a film to show for a given change in film exposure.

Correct : C. A difference in density

9. The range of the specimen thickness that can be adequately recorded on a radiograph is known as the of the radiograph.

Correct : B. Latitude

10. Source-to-object distance, object-to-film distance, and source size are the three factors that control the of the radiograph.

Correct : D. Unsharpness

11. The ‘multi-film’ technique may be used when one radiograph film does not have enough to produce a satisfactory radiograph of a specimen.

Correct : A. Latitude

12. What governs the penetrating power of an X ray beam?

Correct : A. Kilovoltage

13. The shorter the wavelength of X or gamma rays:

Correct : A. The higher their energy

14. A large source size can be compensated for by:

Correct : A. Increasing source-to-specimen distance

15. The maximum film density to which the radiograph should be exposed is dependent upon:

Correct : A. The quality of the film viewer

16. The selection of the proper source-to-film distance is a primary factor in controlling:

Correct : B. Unsharpness

17. When the penumbra on a radiograph measures less than 0.5 mm (0.020 inches), the image will appear to unaided eye of the film interpreter as:

Correct : B. Sharp

18. Two X ray machines operating at same nominal kilovoltage and milliamperage settings:

Correct : D. May give not only different intensities, but also different energies of radiation

19. The fact that gases, when bombarded by radiation, ionise and become electrical conductors make them useful in:

Correct : D. Radiation detection equipment

20. A weld discontinuity which consists of unmelted joint surfaces at the root, and which may be caused by poor fit-up, is called:

Correct : C. Incomplete penetration

21. Which of the following welding discontinuities would be most difficult to image radiographically:

Correct : A. Planar lack of fusion

22. The average energy of a Ir-192 source is approximately:

Correct : D. 1.2 MeV

23. The half-life of Th-170 is approximately:

Correct : B. 129 days

24. If the required exposure time for a 50 Curie Ir-192 source is 4 minutes, what exposure time would be required at 25 Curie source:

Correct : B. 8 minutes

25. Which of the following is not a function of the lead screen placed around radiographic film?

Correct : B. Selectively absorbs scattered radiation

26. Which of the following is a function of the lead screen placed around radiographic film?

Correct : C. Intensifies effects of the primary radiation beam

27. What is the best advantage achieved in exposure time, using front and back lead screens, as compared to exposure time without screens?

Correct : C. 1/2 to 1/3

28. Gamma ray or high voltage X ray radiography, using film without lead screens, is likely to result in:

Correct : A. Mottling of the film

29. An advantage of a double versus a single emulsion film is:

Correct : A. It is higher speed

30. A radiograph is made using film X with an exposure of 10 mA-min. Film density in the area of interest is 1.0. If it is desired to achieve a density of 2.0 in the area of interest, what exposure is required? (Log relative exposure = 1.1 for a density of 1.0 and 1.62 for a density of 2.0)

Correct : D. 33.1 mA-min

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

Correct : A. Transducer wavelength and diameter

32. When a longitudinal wave is incident upon an inclined interface between zero degrees and the first critical angle:

Correct : C. Shear waves and longitudinal waves are produced in the second material

33. The piezoelectric material in a search unit which vibrates to produce ultrasonic waves is called:

Correct : C. A transducer element or crystal

34. 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:

Correct : D. The first critical angle

35. When a longitudinal wave sound beam passes through an acoustic interface at some angle other than zero degrees:

Correct : C. Reflection, refraction and mode conversion will occur

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

Correct : D. All of the above

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

Correct : C. Large grain size

38. Sound waves which travel on the surface of a solid in a manner similar to waves on a water surface are called:

Correct : A. Rayleigh waves

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

Correct : B. A thickness approximately equal to the wavelength

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

Correct : A. Longitudinal

41. When the motion of the particles of a medium is transverse to the direction of propagation, the wave being transmitted is called a:

Correct : B. Shear wave

42. Which of the following test frequencies would generally provide the best penetration in a 12 inch thick specimen of coarse-grained steel?

Correct : A. 1.0 MHz

43. An oscilloscope display in which the screen base line is adjusted to represent the one way distance in a test piece is called a:

Correct : B. B scan display

44. A common use of ultrasonic testing is:

Correct : B. Detecting of sub-surface indications

45. 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:

Correct : A. 20 kHz

46. Y cut crystals produce:

Correct : B. Shear waves

47. 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:

Correct : C. Coaxial cable

48. As ultrasonic frequency increases:

Correct : B. Wavelength decreases

49. In an A scan presentation, the amplitude of vertical indications on the screen represents the:

Correct : A. Amount of ultrasonic sound energy returning to the search unit

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

Correct : C. A discontinuity which is not parallel to the entry surface

51. When a sound beam is reflected:

Correct : B. The angle of reflection equals the angle of incidence

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

Correct : B. The transducer

53. An instrument display in which the horizontal base line represents elapsed time and the vertical deflection represents signal amplitudes is called:

Correct : A. A scan

54. Which of the following circuits provides short duration, high energy pulses which are used to excite the transducer?

Correct : A. The pulse generator

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

Correct : B. B scan

56. Echo amplitude losses may be caused by:

Correct : D. All of the above

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

Correct : D. Greater sensitivity is achieved in the transducer's useable range

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

Correct : C. The power supply

59. Which of the following is a true statement?

Correct : C. Thicker crystals produce lower frequency transducers

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

Correct : D. All of the above

61. The longitudinal wave incident angle at which the refracted shear wave angle equals ninety degrees is called:

Correct : D. The second critical angle

62. The amount of beam divergence from a crystal is primarily dependent on the:

Correct : C. Frequency and crystal size

63. In ultrasonic testing, a liquid coupling medium between the crystal surface and the part surface is necessary because :

Correct : B. An air interface between the crystal surface and the part surface would almost completely reflect the ultrasonic vibrations

64. X cut crystals produce:

Correct : A. Longitudinal waves

65. Lower frequency transducers are normally used:

Correct : D. Where deeper penetration is required

66. All other factors being equal, which of the following modes of vibration has the greatest velocity?

Correct : D. Longitudinal wave

67. 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:

Correct : A. Angulation

68. The angle of a refracted shear wave generated as a sound wave passes at an angle through an acoustic interface is dependant on:

Correct : A. The acoustic impedances of the materials of each side of the interface

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

Correct : C. Loss of discontinuity signal amplitude

70. Wavelength is:

Correct : D. The distance from trough to trough or from peak to peak of a sound wave

71. The velocity of surface waves is approximately shear waves in the same material.

Correct : D. Nine-tenths

72. 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:

Correct : C. The sweep delay

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

Correct : B. It is the least effective generator of ultrasonic energy of all commonly used materials

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

Correct : B. Snell's law

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

Correct : B. Immersion testing

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

Correct : C. Through transmission testing

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

Correct : A. The near field

78. A more highly damped transducer crystal results in:

Correct : A. Better resolution

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

Correct : B. Calibration

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

Correct : A. Material grain size and wavelength are comparable

81. Ultrasonic testing is:

Correct : B. Sound which has a frequency or pitch above the range of the human ear

82. Which technique would most likely be used to examine a weld, with the weld cap still in place?

Correct : B. Angle beam testing

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

Correct : B. 5 MHz

84. Higher frequency transducers are normally used:

Correct : C. In immersion testing applications

85. Typical ultrasonic testing frequencies are:

Correct : D. 1 MHz to 5 MHz

86. ‘25 million cycles per second’ can also be stated as:

Correct : C. 25 MHz

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

Correct : C. It is scattered more by coarse grained material

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

Correct : A. The clock

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

Correct : D. A 25 MHz search unit

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

Correct : B. Only shear waves are produced in the second material

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

Correct : A. Wavelength times frequency

92. The relationship between the longitudinal wave incident angle and the refracted shear wave angle is defined by:

Correct : A. Snell's law

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

Correct : B. Material density × velocity

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

Correct : C. 20 kHz

95. Reference standards containing a series of flat bottom holes of the same diameter at different depths in each block are called?

Correct : B. Distance-amplitude blocks

96. 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:

Correct : B. Obtain a maximum response if the discontinuity is not originally oriented perpendicular to the ultrasonic beam

97. Which of the following transducer materials is the most efficient receiver of ultrasonic energy?

Correct : C. Lithium sulphate

98. An ultrasonic wave in which particle displacement is 90 degrees to the direction of wave propagation is called a:

Correct : B. Shear wave

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

Correct : B. It is one of the most efficient receivers of ultrasonic energy

100. Which of the following materials of the same alloy is most likely to produce the greatest amount of sound attenuation over a given distance?

Correct : B. A coarse grained casting