Take A Free ASNT NDT ET Level 3 Exam Practice Test – Quiz Course

1.

Which of the following is a property of eddy currents induced in a conductor by an encircling coil?

2.

In eddy current testing of ferromagnetic materials, the de-saturating field may be provided by:

3.

In eddy current testing, the theoretical maximum testing speed is determined by the:

4.

Which of the following is not a method that may be used to improve the signal-to-noise ratio?

5.

In Figure 9, ac flowing through a primary coil set-up a magnetic field and causes a flow of eddy currents in the rod. The voltage of the secondary coil is dependent upon:

6.

A product can be viewed in terms of electrical magnetic effects. A diameter change of the product in an encircling coil is:

7.

Spinning probe-type eddy current instruments are most useful in:

8.

A calibration standard may be used with a spinning probe eddy current instrument to:

9.

In a feedthrough encircling coil eddy current system, a calibration standard may be used to:

10.

In a feedthrough encircling coil eddy current system, what would be the purpose of running a calibration defect several times but in various positions (such as top, bottom, left, and right)?

11.

Any handling of equipment used in an eddy current system must take into consideration:

12.

An eddy current system lends itself to quality ratings such as “Quality Numbers” where the product being inspected:

13.

When inspecting material with eddy currents in an automatic handling system, it is advisable to calibrate and adjust the sensitivity levels to:

14.

A distinct advantage of using handling equipment in an eddy current test system is to reduce the error caused by:

15.

Decreased coupling or fill factor results in decreased test sensitivity because:

16.

Why is it desirable to hold the fill factor or lift-off constant?

17.

Which of the following is a property of eddy currents induced in a homogeneous conductor by an encircling coil?

18.

Which factor does not affect the phase shift between the transmitted signal and the reflected signal for a reflection-type coil (assuming the part is nonferromagnetic)?

19.

Lift-off certainly reduces the amplitude of the flux leakage signal. The other significant effect it has on the signal is a change in:

20.

The tubular product parameter having the greatest influence on the flux density of the magnetic field in the part (assuming the magnetizing force, H, remains constant) is the:

21.

When a magnetic bar is placed in the coil’s electromagnetic field, the coil’s reactance is increased. What causes these phenomena?

                   B

equation————=μ

                   H

22.

The reactance component is decreased by placing a conducting object in the coil’s electromagnetic field. Why is this so?

23.

Test coils may be shielded with conducting material or magnetic material to:

24.

When an excitation voltage is applied to a primary winding, only the magnetic flux is in phase and the second magnetic flux is minor. When a test object is inserted in this coil, what action takes place?

25.

The test coil excitation current should be held constant so that the test piece information obtained by an eddy current system will:

26.

Eddy currents flowing in the test object at any depth produce magnetic fields at greater depths, which oppose the primary field, thus reducing its effectiveness and causing what kind of change in current flow as depth increases?

27.

The skin effect causes eddy currents to tend to flow near the surface of the test piece. Which of the following factors alters the skin effect?

28.

Which of the following is not a common undesirable effect on the test coil caused by the testing environment?

29.

There is one function that responds to variations in eddy current flaw and magnetic field conditions. This function actually produces the output signal from the coil. What is this function?

30.

The inductive reactance of a test coil, which is one of the most important impedance quantities, depends upon which of the following?

31.

An ac current produces eddy currents in a test object. The vector H_p represents the secondary ac field in the test piece. What function occurs to produce a workable test situation? (See Figure 10.)

32.

To separate cracks and diameter effects for steel cylinders, the optimum frequencies correspond to f/f_g ratios of less than (see Figure 11):

33.

Thin-walled tubes should be tested for cracks, alloy, or wall thickness at frequency ratios between (see Figure 12):

34.

Figure 13 indicates that the largest eddy current indications from subsurface cracks will occur when the frequency ratio (f/fg ) is:

35.

Figure 13 indicates that the magnitude of a signal from a subsurface, the crack will increase when the frequency ratio (f/fg ):

36.

Figure 14 indicates that when inspecting for surface cracks in nonferromagnetic cylinders, the optimum frequency ratio (f/fg ) is between:

37.

An operating frequency of 100 kHz will have the deepest penetration in the:

38.

As the operating frequency is increased, the impedance of the empty coil:

39.

Disadvantages of using a surface probe coil for the inspection of small-diameter tubing include:

40.

Differential coil systems can be of which of the following types? (see Figure 15)

41.

The sensing element in an eddy current system can be which of the following?

42.

Of the following test coil systems, which would be considered best for the definitive detection of small discontinuities in tubing?

43.

In a test coil system, when the sensing coil is placed near the excitation coil, which of the following statements is true?

44.

In linear time-base equipment:

45.

Filters are used in modulation analysis to:

46.

In modulation analysis, the type of display usually used is:

47.

When the slit technique is used with the linear time base method:

48.

In linear time-base equipment, which type of signal is applied to the horizontal deflection plates?

49.

In the ellipse method, the following (see Figure indication should be interpreted as:

50.

The ellipse test method, used with feed through coils:

51.

Eddy current test instruments that indicate only the magnitude of variation in the total impedance of the test coil are:

52.

In cathode ray tube ellipse testing:

53.

When using an inspection system having an “ellipse display” readout, the signal applied to the vertical input of the scope is related to that applied to the horizontal input as follows:

54.

Which material should be selected to provide the most effective shielding of a test coil from an external RF field?

55.

To allow maximum current to flow through the coil, the capacitor should be adjusted so that:

56.

A primary-secondary coil inspection system is being used. To suppress the primary coil signal induced in the secondary coil, one might:

57.

Which type of readout oscilloscope would be best for examining a nonrepetitive flaw indication during high-speed testing?

58.

An ink-writing strip chart recorder generally provides an accurate representation of its input signal:

59.

A probe coil inspection system is being used to detect cracks in bars. If the cracks have a minimum length of 6 mm (0.25 in.), reliable inspection is best achieved by making the coil diameter:

60.

To ensure reliable flaw detection, the maximum velocity of tubing through an encircling coil must be limited. This limitation is determined by:

61.

Normal test speeds for modulation analysis testing is:

62.

When performing modulation analysis testing, the type of test coil:

63.

A major limitation of modulation analysis is that the system is based on:

64.

Chemical composition, alloy changes, and heat treatment changes usually have a frequency modulation that is:

65.

Modulation would be defined as:

66.

In modulation analysis, the coil’s excitation frequency is being modulated by:

67.

Impedance changes produced by small lift-off variations are greatest when:

68.

When testing for the unknown conductivity of a metal, the measured conductivity is strongly affected by:

69.

In selecting a coil for multifrequency tests:

70.

In developing a multifrequency test, the parameter separation limitations are greatest for those parameters producing:

71.

Mutual inductance describes:

72.

Leakage flux testing is most applicable for the inspection of:

73.

Increasing the heat-treating temperature of nonferrous metals:

74.

Limit frequency, f_g,, is defined when the argument of the mathematical function describing the electromagnetic field within a test specimen is set equal to:

75.

Referring to Figure 17, suppose a test is being conducted at an f/f_g, ratio of 1. Due to a mix of alloys, a new test piece with a conductivity value four times as great as the original material is inserted in the coil. The new f/f_g, the ratio will be:

76.

Figure 18 illustrates the separation of diameter effects and conductivity effects:

77.

Figure 19 illustrates:

78.

Figure 20 illustrates the impedance diagram for tubing where the ratio of the inside diameter to the outside diameter is 80 percent. It is possible to calculate an approximate limit frequency, f_g, by using only the outside diameter. Thus, the maximum test sensitivity for effects of conductivity, wall thickness, and cracks occurs at a frequency ratio of:

79.

The electromagnetic field in a test specimen during eddy current testing is described by:

80.

In flux leakage testing of wire rope, the system of two different diameter search coils is frequently used. What is the main reason for using such a system? (See Figure FL-8.)

81.

In flux leakage testing of wire rope, two separate outer broken wires will produce two separate indications if there is sufficient distance between the breaks. What is the maximum rope speed in feet per minute that would produce two separate indications when the cut-off frequency of the recorder is 60 kHz and the breaks are 25 mm (1 in.) apart? (See Figure FL-9.)

82.

Which devices are used to detect flux leakage?

83.

In Figure FL-10, the flux leakage at slot A will be _______than that at slot B.

84.

In a properly operating flux leakage system, pipe defects occurring at increased depths from the surface will generate signals with:

85.

Lift-off reduces the amplitude of the flux leakage signal. The other significant effect it has on the signal is:

86.

Eddy current shielding, the name given to the unidirectional eddy current flow in products inspected by the flux leakage method, is caused by:

87.

A flux leakage pipe inspection system with two inspection heads, each having 152 mm (6 in.) long scan paths and rotating at 180 rpm on a 178 mm (7 in.) diameter tube, can have a maximum throughput speed of per minute for 100% inspection coverage.

88.

A flux leakage pipe inspection system with two inspection heads, each having 152 mm (6 in.) long inspection areas and rotating at 180 rpm on a 178 mm (7 in.) diameter pipe, would require a throughput speed of- per minute to provide a 110% inspection coverage.

89.

The tubular product parameter having the greatest influence on the flux density of the magnetic field in the part (assuming the magnetizing force (H) and the material’s permeability remains constant) is the:

90.

A defect having an inclined angle to the surface has a flux leakage that is (see Figure FL-11):

91.

Too high a rotational test speed or too high an active pole rotating head speed can cause the loss of an indication from an ID defect. What can this be attributed to?

92.

A current-carrying conductor is surrounded by a tube (see Figure FL -12). Magnetic fields exist in the tube if the tube is made of:

93.

A tube is magnetized by passing a uniform current through the tube. There are inside and outside defects in the tube (see Figure FL-13). The two defects have the same dimension and geometry. The defect signal strength:

94.

A discontinuity in a steel wire rope may be detected with a dc magnetic instrument if:

95.

What is the SI unit for magnetic flux density?

96.

What is the SI unit for magnetic field strength?

97.

What is the SI unit for magnetic permeability?

98.

A ferromagnetic part can be demagnetized by:

99.

Figure FL-14 shows an arrangement of probe coils in a Forester probe used for measuring:

100.

In flux leakage testing the maximum permissible speed of probe or tube movement with respect to the other is: