Eddy Current Practise

  • Grade 11th
  • ASTM E426
  • ISO 15548
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| Attempts: 4,393 | Questions: 92 | Updated: May 14, 2026
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1. A term to define the phenomenon where, at very high frequencies, the eddy current flow is resrticted to an extremely thin outer layer of the conductor is:

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About This Quiz
Magnetic Field Quizzes & Trivia

Theory and application of non destructive testing method eddy current

2.

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2. Eddy current testing relies on the principle of:

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3. A term used to define 2 or more coils electrically connected in opposition such that
any electromagentic condition which is not common to both a test specimen and a
reference specimen will produce an unbalance in the system is:

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4. The thickness of nonconductive coatings on a conductive base can be most simply measured
by:

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5. The symbol commonly used to signify impedance is:

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6. The actual frequency used in any specific eddy current inspection should be selected
on the basis of the:

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7. The conductivity value for a metal is a function of the :

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8. Tubing is generally inspected using:

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9. When testing by the eddy current method, discontinuities will be most easily detected when the eddy currents are:

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10. The atoms of a metal showing magnetic characteristics are grouped into regions which
are the smallest known permanent magnets. These regions are called:

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11. When a rod is placed in an encircling type of coil, the density of eddy currents will be greatest:

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12. When the voltage applied to a circuit and the current through the circuit both reach their
maximums and minimums at the same time, the voltage and current are:

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13. When testing ferrous materials, a small but detectable portion of the magnetic flux in the
material will pass outside the metal when a surface discontinuity is encountered. This flux is
called:

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14. When testing small parts in an eddy current encircling coil for permeability measurements,
which of the following test parameters may be considered important?

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15. The term used to define the value of H field required to decrease the remanence of
a material to zero is:

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16. The magnetizing force of an eddy current test coil is usually designated by the:

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17. The magnetic field generated by eddy currents induced in a test specimen:

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18. When a nonmagnetic rod is placed inside an eddy current test coil:

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19.  A term used to describe the effect observed due to a change in the electromagnetic coupling
between a test specimen and a probe coil when the distance of separation between them
is varied is:

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20. The magnetic domains in an unmagnetized ferromagnetic material are:

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21. The inductive reactance of a test coil can be calculated using the formula:

Submit

22. When eddy current testing a nonferrous material, the choice of test frequency is determined
by the :

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23. The heating effect in magnetic materials caused by work required to rotate magnetic
domains can be eliminated by:

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24. Which of the following materials would have the highest resistivity value?

Submit

25. The inductive reactance of a coil is measured in units of:

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26. When the electrical current in an eddy current coil reverses direction:

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27. A major problem associated with eddy current test method is the:

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28. When a magnetic material is placed in a region of an applied magnetizing force(H), magnetic
field (B) is developed in the material by means of:

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29. In eddy current testing, the specimen is coupled to the test coil by:

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30. When the H field strength around a material is increased and then decreased to zero,
the induction field B within the part does not return to zero, the term to define this B
value when H has returned to zero is:

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31. Frequency ratio f/f can be defined as:

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32. The impedance of a test coil usually can be represented by the vector sum of:

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33. Which three parameters of a test specimen most significantly influence eddy current testing results?

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34. A term used to define the timing relationship invovled in alternating current signals is:

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35. The fill factor when a 1/2 inch diameter bar is inserted in a 1 inch diameter coil is:

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36. Which of the following could be used to suppress unwanted high frequency harmonics?

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37. An out-of-phase condition between current and voltage:

Submit

38. Which of the following conditions is not important when selecting specimens to be used
as reference standards?

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39.  term fill factor applies to:

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40. For age hardenable aluminum and titanium alloys, changes in hardness are indicated by
changes in:

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41. Which of the following methods may be used to improve the signal-to-noise ratio of an eddy
current test system?

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42. At a fixed test frequency, in which of the following materials will the eddy current
penetration be greatest?

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43. A method of minimizing the effect of indications caused by gradual dimensional changes while
retaining the indications caused by discontinuities is to:

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44. In a test coil consisting of both a primary and secondary winding, the voltage across the
secondary is a function of:

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45. 2 TEST COILS ARE OFTEN USED IN A BRIDGE CIRCUIT

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46. A term used to define a material having a permeability less than that of a vacum is

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47. Which of the following would be easier to detect in tubing by the eddy current
method using self comparison differential coil arrangement?

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48. Which of the following materials would be more likely used as a mounting material for a probe
coil?

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49. When testing tubing, using an encircling (OD) coil, What is the phase relationship of
the output signals from identical ID and OD discontinuities?

Submit

50. Doubling the number of turns on a coil will:

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51.  When conducting an eddy current test, variations in the test material can be detected
as variations in:

Submit

52. An eddy current system using handling equipment with automatic marking of the defective areas primarily makes it possible to:

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53. The term used to define the difference between actual instrument output and expected
output as defined by a straight line calibration curve is:

Submit

54. To eliminate any dependence upon the number of turns of a test coil, the inductance
values of an impedance diagram are:

Submit

55. A term used to define a surface or internal rupture which is attributed to pprocessing
at low a temperature or excessive working or metal movement during the forging, rolling, or extruding operation is:

Submit

56. The ratio of a material's flux density to a test coil's magnetizing force,(B/H), can be
used to determine the material's:

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57. The flux density in a magnetic material is usually designated by the :

Submit

58. When eddy current testing by the linear time-base method, what is applied to the vertical
deflection plates of a cathode ray tube when a condition of unbalance exist between the test specimen and the reference standard?

Submit

59. When eddy current testing tubing with a system that includes a frequency discriminating circuit,
which of the following variables wolud be classified as a high frequency variable?

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60. The ratio of the specific diameter of a probe to the minimum discontinuity of interest should be:

Submit

61. If the characteristic frequency (fq) of a material is 125 hz, the test frequency required
 to give an f/fq ratio of 10 would be:

Submit

62. The penetration of eddy currents in a conductive material is decreased when:

Submit

63. In order to decrease the effect on conductivity readings due to variations in test part thickness:

Submit

64. If the test frequency increases while field strength is held constant, the surface  density:
eddy current

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65. Which of the following coil arrangements would eliminate or decrease the effects of minor variations in diameter, chemical  composition, hardness, etc, which occur gradually
 along the length of a wire?

Submit

66. Which of the following is not a commonly used eddy current testing readout mechanism?

Submit

67. The impedance change of an eddy current test coil due to a change in the test part
characteristics can be most easily analyzed as a combined change in:

Submit

68. A decrease in conductivity is equivalent to:

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69. The formula used to calculate the impedance of an eddy current test coil is:

Submit

70. A term used to define an eddy current test coil which uses magnetic material to purposely
shape the magnetic field is:

Submit

71. The circuits which make it possible to minimize the effect of signals caused by variables
of no interest on the readout mechanism are based on differences in:

Submit

72. When testing magnetic materials in a ac field, increasing the field strength:

Submit

73. When eddy current testing by the ellipse method, the normal indication when the test specimen and reference standard are the same is approximately:

Submit

74. A term used to define a surface coil mounted so that the coil can be rotated about the
circumference of a test specimen is:

Submit

75. A term used to define an instrumentation technique which discriminates between
variables in the test part by the different phase angle changes which these conditions
produce in the test signal is:

Submit

76. The  vector-point, ellipse, and linear time-base methods are all subdivisions of the:

Submit

77. As the fill factor decreases, the impedance variation of a pickup coil produced
by a given chaange in conductivity will:

Submit

78. It is frequently possible to separate the conductivity variable from the permeability and
dimensional variables when using:

Submit

79. A term used to define a system which indicates only the magnitude of variations in the total
coil impedance regardless of the phase or direction in which it occurs on an impedance plane is:

Submit

80. When a coil's magnetizing force is applied to a ferromagnetic material, the flux density
in the material is:

Submit

81. In modulation analysis testing, which of the following would not modulate the test
frequency applied to the test coil?

Submit

82. When eddy current testing by ellipse method, one variable may be indicated by the angle
of the ellipse or straight line while another variable may be indicated by the:

Submit

83. Impedance diagrams have been mathematically derived and experimentally verified for materials
of any conductivity and permeability having rectangular, cylindrcal, or spherical symmetry. To
test all specimens of similar geometry under the same condition, it is only necessary to choose a test frequency, (f), so that frequency ratio f/f lies at the same point on the impedance diagram for each specimen. This principle is based upon:

Submit

84. A term to define a property of a test system which enables the separation of signals due
to discontinuities in the test specimen that are located in close proximity to each other is:

Submit

85. A term used to define any change in a sinusoidal signal when the output is not a linear
reproduction of the input is:

Submit

86. Which of the following is not a factor that affects the inductance of an eddy current test coil?

Submit

87. In inspecting ferromagnetic materials, relatively low frequencies are normally used because
of the:

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88. If the conductivity of a test part in an eddy current test coil decreases, the magnitude
of the eddy currents at a given depth in the test specimen:

Submit

89. An eddy current test coil's magnetic field intensity in air:

Submit

90. When eddy current testing by the linear time base method, what is applied to the vertical
deflection plates of a cathod ray tube when the test specimen and reference standard are
the same and the balance controls are properly adjusted?

Submit

91. To be useful, limit frequency equations must be:

Submit

92. The use of magnetic shielding around the exciting coil will generally:

Submit
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A term to define the phenomenon where, at very high frequencies, the...
Eddy current testing relies on the principle of:
A term used to define 2 or more coils electrically connected in...
The thickness of nonconductive coatings on a conductive base can be...
The symbol commonly used to signify impedance is:
The actual frequency used in any specific eddy current inspection...
The conductivity value for a metal is a function of the :
Tubing is generally inspected using:
When testing by the eddy current method, discontinuities will be most...
The atoms of a metal showing magnetic characteristics are grouped into...
When a rod is placed in an encircling type of coil, the density of...
When the voltage applied to a circuit and the current through the...
When testing ferrous materials, a small but detectable portion of the...
When testing small parts in an eddy current encircling coil for...
The term used to define the value of H field required to decrease the...
The magnetizing force of an eddy current test coil is usually...
The magnetic field generated by eddy currents induced in a test...
When a nonmagnetic rod is placed inside an eddy current test coil:
 A term used to describe the effect observed due to a change in...
The magnetic domains in an unmagnetized ferromagnetic material are:
The inductive reactance of a test coil can be calculated using the...
When eddy current testing a nonferrous material, the choice of test...
The heating effect in magnetic materials caused by work required to...
Which of the following materials would have the highest resistivity...
The inductive reactance of a coil is measured in units of:
When the electrical current in an eddy current coil reverses...
A major problem associated with eddy current test method is the:
When a magnetic material is placed in a region of an applied...
In eddy current testing, the specimen is coupled to the test coil by:
When the H field strength around a material is increased and then...
Frequency ratio f/f can be defined as:
The impedance of a test coil usually can be represented by the vector...
Which three parameters of a test specimen most significantly influence...
A term used to define the timing relationship invovled in alternating...
The fill factor when a 1/2 inch diameter bar is inserted in a 1 inch...
Which of the following could be used to suppress unwanted high...
An out-of-phase condition between current and voltage:
Which of the following conditions is not important when selecting...
 term fill factor applies to:
For age hardenable aluminum and titanium alloys, changes in hardness...
Which of the following methods may be used to improve the...
At a fixed test frequency, in which of the following materials will...
A method of minimizing the effect of indications caused by gradual...
In a test coil consisting of both a primary and secondary winding, the...
2 TEST COILS ARE OFTEN USED IN A BRIDGE CIRCUIT
A term used to define a material having a permeability less than that...
Which of the following would be easier to detect in tubing by the eddy...
Which of the following materials would be more likely used as a...
When testing tubing, using an encircling (OD) coil, What is the phase...
Doubling the number of turns on a coil will:
 When conducting an eddy current test, variations in the test...
An eddy current system using handling equipment with automatic marking...
The term used to define the difference between actual instrument...
To eliminate any dependence upon the number of turns of a test coil,...
A term used to define a surface or internal rupture which is...
The ratio of a material's flux density to a test coil's magnetizing...
The flux density in a magnetic material is usually designated by the :
When eddy current testing by the linear time-base method, what is...
When eddy current testing tubing with a system that includes a...
The ratio of the specific diameter of a probe to the minimum...
If the characteristic frequency (fq) of a material is 125 hz, the test...
The penetration of eddy currents in a conductive material is decreased...
In order to decrease the effect on conductivity readings due to...
If the test frequency increases while field strength is held constant,...
Which of the following coil arrangements would eliminate or decrease...
Which of the following is not a commonly used eddy current testing...
The impedance change of an eddy current test coil due to a change in...
A decrease in conductivity is equivalent to:
The formula used to calculate the impedance of an eddy current test...
A term used to define an eddy current test coil which uses magnetic...
The circuits which make it possible to minimize the effect of signals...
When testing magnetic materials in a ac field, increasing the field...
When eddy current testing by the ellipse method, the normal indication...
A term used to define a surface coil mounted so that the coil can be...
A term used to define an instrumentation technique which discriminates...
The  vector-point, ellipse, and linear time-base methods are all...
As the fill factor decreases, the impedance variation of a pickup coil...
It is frequently possible to separate the conductivity variable from...
A term used to define a system which indicates only the magnitude...
When a coil's magnetizing force is applied to a ferromagnetic...
In modulation analysis testing, which of the following would not...
When eddy current testing by ellipse method, one variable may be...
Impedance diagrams have been mathematically derived and experimentally...
A term to define a property of a test system which enables the...
A term used to define any change in a sinusoidal signal when the...
Which of the following is not a factor that affects the inductance of...
In inspecting ferromagnetic materials, relatively low frequencies are...
If the conductivity of a test part in an eddy current test coil...
An eddy current test coil's magnetic field intensity in air:
When eddy current testing by the linear time base method, what is...
To be useful, limit frequency equations must be:
The use of magnetic shielding around the exciting coil will generally:
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