9/4/13 Eddy Current Inspection 50 Question Quiz

Eddy Current Inspection 50 Question

Quiz

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The higher the inductance of a coil at a given frequency:

1 The more penetrating the eddy currents will be
The less sensitive the coil will be
The more sensitive the coil will be
None of the above

A probe that is often intended to be used in contact with the test

2 surface is called a:
Reference probe
Surface probe
Transmission probe
Reflection probe

When testing for subsurface flaws, the frequency should be:

3 As high as possible
As low as possible
Calculated to produce a 90o difference between the liftoff and flaw
signals
None of the above

LPF stands for:

4 Low Pulse Frequency
Low Pass Filter
Last Pass Filter
Low Pass Frequency

Discontinuities, such as delaminations, that are in a plane that is

5 parallel with the test surface will likely:

Be easily detected with a surface probe

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9/4/13 Eddy Current Inspection 50 Question Quiz

Be easily detected with an internal probe

Be easily detected with an external probe
None of the above

Sliding probes usually operate in the:

6 Reflection mode
Through-transmission mode
Pulsed mode
Differential mode

When using eddy currents to measure the thickness of a nonconductive

7 coating applied to a conductive base, the measurement is based on:
A frequency change due to liftoff
An impedance change due to a change in conductivity
An impedance change due to liftoff
Both A and C

A probes that can be used to inspect the entire circumference of test

8 objects are:
Encircling or bobbin probes
Circumference probes
Pencil probes
None of the above

Probes for inspection of pipe and tubing are typically of the:

9 Surface probe variety
Bolt hole variety
Bobbin (ID) variety
All of the above are correct

Probe shielding is used to:

10 Shape the eddy currents to the curvature of the part
Reduce the inductive coupling of the probe and part
Increase the probe impedance
Reduce the effects of nonrelevant features in close proximity to the probe

Which type of probe has a long slender housing to permit inspection in

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9/4/13 Eddy Current Inspection 50 Question Quiz

11 restricted spaces?

Pancake probes
Pencil probes
Encircling probes
Sliding probes

Which component features should be similar to the reference standard?

12 Material thickness
Material geometry
Material conductivity
All of the above

When a probe is brought near a conductive but nonmagnetic material,

13 the coil's inductive reactance will:
Increase
Decrease
Remain the same
Remain the same until the probe touches the material

Which type of probe is most often used to inspect the inside diameter
14 of a machined hole?
Pencil probes
Surface probes
Bolt hole probes
Bobbin probes

The HPF allows:

15 Low frequencies to pass and filters out the high frequencies
High frequencies to pass and filters out the low frequencies
For the combined frequencies to be adjusted to a harmonic balance
The shape of the waveform to be clipped beyond it frequency balance

Which of the following are a common eddy current reference standard?

16
Conductivity standards
Tube discontinuity standards
Hole discontinuity standards
All of the above
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9/4/13 Eddy Current Inspection 50 Question Quiz

Drilled holes are commonly used to represent:

17 Pitting
Cracks
Delaminations

None of the above

Use of the HPF is not recommended:

18 On thin parts
On thick parts
When scanning manually
On ferrous parts

The principles of operation of the most commonly used eddy current

19 instruments are based on:
Roentgen's formulas
Maxwell's inductance bridge
Reciprocity
The Inverse Square Law

Relative permeability is:

20 The permeability in a vacuum
A unitless value
The ratio of the measured permeability and the permeability in a vacuum
Both B and C

When an absolute probe is brought near a ferromagnetic material, the

21 inductive reactance of the coil will:
Remain unchanged
Increase because the material will concentrate the magnetic field in and
around the coil
Decrease because the material will concetrate the magnetic field in and
around the coil
Decrease because the magnetic field of the coil will be weakened by the
material

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9/4/13 Eddy Current Inspection 50 Question Quiz

22
The main function of the LPF is to:
Control probe wobble
Adjust the machine to the proper conductivity standard
Shift the waveform to the left of the screen
Remove high frequency interference noise

When making a conductivity measurement, the thickness of the

23 material should be at least ___ times the standard depth of penetration.
1
2
3
4

The HPF is used to:

24 Eliminate low frequencies which are produced by slow changes, such as
a conductivity shift
Adjust the bandwidth to a neutral frequency in order to maximize depth
of penetration
Remove any standing waves in the output signal
Shift the waveform from positive to negative when a rejectable defect is
identified

Phase lag:
25 Increase with discontinuity depth
Decrease with discontinuity depth
Is the same as phase angle
Is the same as the angle separating the liftoff and flaw signals on an
impedance plane

Which type of probe is most commonly sued to inspect solid products

26 such as bar stock?
Bobbin probes
Surface coils
Encircling coils
Pencil probes

Probe shielding and loading are sometimes used to:

27
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9/4/13 Eddy Current Inspection 50 Question Quiz

Prevent external electrical interference

Limit the spread and concentrate the magnetic field of the coil
Magnetically saturate the part
None of the above

Eddy currents are generated when:

28 A conductive material is placed in a changing magnetic field
When a conductive material is moved through a static magnetic field
When a static magnetic field is moved across the surface of a conductive
material
All of the above

Sliding probes are used to test:

29 Large flat surfaces
Inside bolt holes
In radiuses
Around the edges of fasteners

The higher the frequency of the current used to drive the probe, the:
30 More effective shielding will be due to skin effect
Deeper the eddy currents will penetrate
Stronger the probe's magnetic field will be
Both A and C

What is the relationship between electrical conductivity and electrical

31 resistivity?
They are directly proportional
They are not related
One is the inverse of the other
It depends on the test frequency

When testing for surface flaws, the probe drive frequency used:
32 Should be as high as possible
Should be as low as possible
Depends on the conductivity and permeability of the material
Depends only on the material conductivity

The coil in an eddy current probe is most often made from:

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9/4/13 Eddy Current Inspection 50 Question Quiz

33 Iron
Copper
Silver
Platinum

Inductance is identified by the letter:

34 L
M
Z
X

Inductance is caused by:

35 The interaction of a changing magnetic field with a conductor
Direct current
Resistance in the coil
None of the above

An eddy current test circuit will have:

36 Resistance
Inductive reactance
A small amount of capacitance
All of the above

A bolt hole probe and scanner is used to inspect:

37 Flat surfaces
Radiuses
Holes
Both B and C

When using the liftoff trace of an impedance plane instrument to

38 distinguish between several materials with high electrical conductivity,
it is best to test using a:
High frequency
Variable frequency
Low frequency
None of the above

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9/4/13 Eddy Current Inspection 50 Question Quiz

Eddy current testing can be used to:

39 Detect surface and near surface cracks
Measure electrical conductivity
Measure the thickness of nonconductive coatings on plastics
Both A and B

The depth of penetration is affected by:

40 Magnetic permeability
Electrical resistivity
Probe drive frequency
All of the above

Filtering is applied to the received signal and, therefore:

41 It should be added to the base signal
It is not directly related to the probe drive frequency
Should be added to the pick-up coil
Should be subtracted from the amplitude of the dB

Probes with iron cores tend to:

42 Be more sensitive than air core probes and less affected by probe wobble
Be more difficult to use
Increase the background noise of the signal
Both B and C

In almost all cases, eddy current inspection procedures require the

43 equipment to be calibrated to:

A reference standard
An identified defect
A crack which is � the rejection criteria
A crack twice the rejection criteria

When maintaining constant liftoff is a problem, what type of probe

44 should be used?
A absolute probe
A differential probe
A reflection probe
Both B and C
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9/4/13 Eddy Current Inspection 50 Question Quiz

The main purpose of an iron core in a probe is to:

45 Shift the transmission of eddy currents in order to decrease penetration
Allow the probe to operate at a higher frequency
Concentrate the magnetic field near the center of the probe
Allow testing of very dense materials

HPF stands for:

46 High Pulse Filter
Harmonic Pulse Filter
High Pass Filter
High Pulse Factor

Scanning speed must be controlled:

47 When using a small transducer
When using a large transducer
When using a high pass filter
When using a large low frequency probe

What material(s) is/are commonly used to shield an eddy current

48 probe?
Ferrite
Aluminum
Lead
Both A and B

Some common classifications of probes include:

49 Surface probes
Bolt hole probes
ID probes
All of the above

Most surface probe coils are wound so that:

50 They transmit a frequency that will slightly resonate the part surface
They create a static magnetic field
The axis of the coil is perpendicular to the test surface
Both B and C

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9/4/13 Eddy Current Inspection 50 Question Quiz

C opyright � T he C ollaboration for N D T E duc ation..

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