1. Magnetic particles testing is most likely to find subsurface discontinuities in:
Correct : A. Soft steels with high permeability
2. Which of the following is not an advantage of magnetic particles testing?
Correct : C. Most reliable for finding surface cracks in all types of material
3. Which of the following does not represent a limitation of magnetic particle testing?
Correct : D. The ability to detect discontinuities filled with foreign material
4. The most effective NDT method for locating surface cracks in ferromagnetic materials
is:
Correct : C. Magnetic particle testing
5. Which of the following may cause magnetic particle test indications?
Correct : D. All of the above
6. A discontinuity which is produced during solidification of the molten metal is called:
Correct : A. Inherent
7. Pipe would be classified as what type of discontinuity?
Correct : A. Inherent
8. A seam would be classified as what type of discontinuity?
Correct : B. Processing
9. A lamination in steel plate would be classified as what type of discontinuity?
Correct : B. Processing
10. An internal rupture caused by working steel at improper temperatures is called a:
Correct : C. Forging burst
11. Cracks which are caused by alternating stresses above a critical level are called:
Correct : D. Fatigue cracks
12. Cracks which are caused by a combination of tensile stress and corrosion are called:
Correct : A. Stress corrosion cracks
13. Which of the following are ferromagnetic materials?
Correct : D. Iron, cobalt, nickel
14. The reverse magnetising force necessary to remove a residual magnetic field from a
test piece after it has been magnetically saturated is called:
Correct : B. Coercive force
15. Magnetic lines of force enter and leave a magnet at:
Correct : D. Poles
16. The ease with which a magnetic field can be established in a test piece is called:
Correct : C. Permeability
17. Opposition to establishment of a magnetic field is called:
Correct : A. Reluctance
18. The ability of a material to remain magnetic after the magnetising force is removed is
called:
Correct : B. Retentivity
19. A magnetic field which is contained completely within the test piece is called a:
Correct : C. Circular field
20. Which of the following produces a circular field?
Correct : B. Head shot
21. A technique used to find transverse discontinuities at the ends of longitudinally
magnetised bars by the use of transient currents is called:
Correct : B. A fast break technique
22. A leakage field is strongest when a discontinuity interrupts the magnetic flux lines at
an angle of:
Correct : C. 90 degrees
23. The best method of inducing a circular field in a tube is by a:
Correct : A. Central conductor
24. Magnetic flux density is zero at:
Correct : D. The centre of a bar magnetised with a head shot
25. Magnetic flux density is highest at:
Correct : D. The inside surface of a ferromagnetic tube magnetised with a central conductor
26. An important consideration when using a direct contact method is:
Correct : C. Preventing arc burns
27. A prod method would be most sensitive to cracks:
Correct : A. Parallel to a line connecting the prod contact points
28. When using prods, arc burns may be caused by which of the following?
Correct : D. All of the above
29. The important difference between AC and DC current for magnetic particle testing
purposes is:
Correct : C. The DC magnetic fields are more penetrating
30. The ‘skin’ effect would be most noticeable in which of the following?
Correct : D. A nonmagnetic conductor carrying a 50 Hz AC current
31. The most common source of DC current for magnetic particle testing is:
Correct : B. Rectified AC
32. Fields generated in ferromagnetic material with AC current are useful for locating:
Correct : B. Surface cracks
33. A common rule of thumb to use for current required in circular magnetisation:
Correct : B. 1000 ampere turns/25mm of diameter
34. The formula, NI = 45000/(L/D), is used to calculate the proper magnetising current
for:
Correct : D. Coil magnetisation
35. The formula, NI = 45000/(L/D), gives proper magnetising current for a coil, regardless
of coil size as long as:
Correct : A. The test piece is not larger than 1/10 the cross sectional area of the coil
36. For direct contact magnetising methods, the magnetic field is oriented in what direction
relative to the current direction?
Correct : C. At 90 degrees
37. For direct contact magnetising methods, current should be flowing in what direction
relative to expected discontinuities?
Correct : A. Parallel
38. What is the magnetic field strength at the surface of a 100 mm diameter bar as compared
to that at the surface of a 50 mm diameter bar, each carrying 1000 amps of current?
Correct : B. One half
39. What is the magnetic field strength at the surface of a 25mm diameter bar as compared
to that at the surface of a 50mm diameter bar, each carrying 1000 amps of current?
Correct : A. Twice
40. The magnetic field outside a conductor decreases:
Correct : B. In a linear manner
41. How is the magnetic field strength at the surface of a magnetic conductor having permeability, µ, related to the magnetic field strength, F, at the surface of a nonmagnetic conductor carrying the same current?
Correct : B. Same
42. Compared to the magnetic field strength at the outer surface, the magnetic field strength,
at the centre of a hollow, nonmagnetic conductor carrying DC current is:
Correct : C. Zero
43. How is the magnetic field strength, F, just outside a magnetic conductor having permeability, µ, related to that just outside a nonmagnetic conductor of the same size, carrying the same current?
Correct : B. Same
44. Which of the following describes the shape of particles used for dry magnetic particle
testing?
Correct : D. Mixture of elongated and globular
45. Which of the following particles would be most sensitive?
Correct : B. Dry
46. Which of the following colours is readily available for magnetic particle test powder?
Correct : D. All of the above
47. A magnetic particle testing technique in which the test piece is magnetised and
magnetic particles applied after the magnetising force has been removed is called the:
Correct : C. Residual method
48. Which of the following characteristics would be most important in a test piece which
is to be tested using the residual method?
Correct : A. High rententivity
49. The wet method is superior to dry particles for detecting:
Correct : B. Fine surface cracks
50. Selection of magnetic particle colour is based on:
Correct : C. Obtaining maximum contrast with the test piece background
51. The residual method is applicable to:
Correct : A. Surface discontinuities only
52. Highest sensitivity to fine surface cracks would be obtained by which of the following
techniques?
Correct : C. Continuous field, wet method
53. A residual field is always less than a continuous field because?
Correct : B. The magnetic field, as shown by a hysteresis curve, is less when there is no magnetising force
54. Where possible, circular magnetisation is preferable to longitudinal magnetization
because:
Correct : D. None of the above is true
55. Which of the following is a disadvantage of the dry method?
Correct : B. Superior sensitivity for fine surface cracks
56. Which of the following is an advantage of the dry method
Correct : A. Good sensitivity for subsurface discontinuities
57. Loss of fine particle sizes due to re-use of dry particles would probably lead to:
Correct : B. Loss of sensitivity to finer discontinuities
58. Which of the following is a disadvantage of the wet method?
Correct : D. Excellent detection of completely subsurface discontinuities
59. Which of the following is an advantage of the wet method?
Correct : B. Ease of bath recovery and re-use
60. The primary reason for using water rather than oil as a suspension medium for wet
method baths is that:
Correct : B. Bath flammability hazards are eliminated
61. A disadvantage of fluorescent magnetic particles is:
Correct : A. Darkened area and black light are required
62. A common physiological effect of black light inspection on the inspector is:
Correct : C. Eye fatigue
63. A common physiological effect of black light inspection on the inspector is:
Correct : C. Eyeball fluorescence
64. Which of the following represents ultraviolet light of wavelengths which are
potentially injurious (1 Å = 10-10m)
Correct : A. 2000 to 3200Å
65. Dyes which receive light at one wavelength and re-emit light of another wavelength
are called:
Correct : D. Fluorescent
66. Most fluorescent dyes used for magnetic particle testing fluoresce what colour?
Correct : B. Yellow green
67. The best available source of black light for inspection is:
Correct : A. The mercury vapour lamp
68. Which of the following would be likely to cause variations in the output of an
inspection black light?
Correct : D. All of the above
69. The temperature above which steels become nonmagnetic is called the:
Correct : B. Curie point
70. The temperature above which most soft steels become nonmagnetic is about:
Correct : D. 754ºC (1390ºF)
71. The most common method of demagnetising small test pieces is:
Correct : C. Passing through an AC coil
72. Demagnetisation with reversing DC is more effective than AC because:
Correct : A. DC is more penetrating
73. The type of discontinuity which magnetic particle testing most effectively locates is:
Correct : D. Surface cracks
74. An indication which is formed when two pieces of magnetised steel come in contact
with each other is called:
Correct : B. Magnetic writing
75. Magnetic particle test indications which are due to cold work can best be removed by:
Correct : D. Heat treating
76. Which of the following might cause non-relevant indications?
Correct : D. All of the above
77. An inspection for surface and subsurface discontinuities in ferromagnetic welds would
best be accomplished by which of the following techniques?
Correct : A. Prods
78. A continuous linear indication along the centre of a fillet weld would most likely be a:
Correct : C. Root indication
79. Wet magnetic particle bath strength is checked by which of the following?
Correct : C. Settling test
80. Which of the following describes the best technique for applying dry magnetic
particles to a test piece?
Correct : D. Shake or dust the powder onto the test piece with minimum velocity
81. An advantage of AC equipment over DC is:
Correct : C. AC makes the magnetic particles more mobile on the test surface
82. When the orientation of likely discontinuities is unknown, what is the minimum
number of magnetising operations required to perform an adequate test?
Correct : B. 2
83. Maximum practical prod spacing is about:
Correct : B. 200 mm
84. Magnetic lines of flux which are parallel to a discontinuity produce:
Correct : C. No indications
85. The area of maximum induced field strength using a yoke is:
Correct : C. The area directly between the poles
86. A minimum of external poles are produced by what type of magnetisation?
Correct : C. Circular
87. A split coil would most likely be used with a:
Correct : D. Portable magnetic particle unit
88. The most common harmful effect of exposure to black light is:
Correct : A. Eyeball fluorescence
89. Which of the following types of magnetic fields may be present without any external
evidence?
Correct : A. Circular
90. The primary reason for using water rather than oil as a suspension medium for wet
method baths is that
Correct : B. Bath flammability hazards are eliminated
91. Wet magnetic particle strength is checked by which of the following?
Correct : C. Settling test
92. A residual circular field may be objectionable because:
Correct : B. Machining may create external poles
93. A prod method would be most sensitive to cracks:
Correct : A. Parallel to a line connecting the prod contract points
94. Maximum practical prod spacing for a 2000 amp unit is about:
Correct : B. 200 mm
95. Demagnetisation with reversing DC is more effective than AC because:
Correct : A. DC is more penetrating
96. Fluorescent magnetic particle indications should be inspected under
Correct : C. Black light
97. Cracks which are caused by a combination of tensile stress and corrosion are called:
Correct : C. Stress corrosion cracking
98. The type of discontinuity potentially most harmful to the useful life of a part is:
Correct : D. Surface cracks
99. Magnetic particle test indications which are due to cold work can best be removed by:
Correct : D. Re-heat treating
100. Which of the following might cause non relevant indications?