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ASNT Study Guide - Chapter 4 > Electromagnetic Testing (ET) Review Questions > Flashcards

Electromagnetic Testing (ET) Review Questions Flashcards

1
Q 
1. Eddy currents are circulating electrical currents induced in conductive materials by:
A. Continuous direct current
B. Gamma rays
C. An alternating magnetic field
D. A piezoelectrical force
A

C. An alternating magnetic field

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2
Q 
2. The method used to generate eddy currents in a test specimen by means of a coil can most closely be compared with the action of a:
A. Transformer
B. Capacitor
C. Storage battery
D. Generator
A

A. Transformer

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3
Q 
3. Eddy current testing relies on the principle of what?
A. Magnetostriction
B. Electromagnetic induction
C. Piezoelectric energy conversion
D. Magnetomotive force
A

B. Electromagnetic induction

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4
Q
  1. When the electrical current in an eddy current coil reverses direction, the:
    A. Direction of the eddy currents in the test part remains the same
    B. Eddy currents in the test part will change phase by 45 degrees
    C. Direction of the eddy currents in the test part also reverse
    D. Eddy currents in the test part will change phase by 90 degrees
A

C. Direction of the eddy currents in the test part also reverse

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5
Q 
5. In order to generate measurable eddy currents in a test specimen, the specimen must be:
A. An electrical conductor
B. An electrical insulator
C. A ferromagnetic material
D. A non magnetic material
A

A. An electrical conductor

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6
Q
  1. The magnetic field that induce the eddy currents:
    A. Oppose the magnetic fields that induce the eddy currents
    B. Reinforces the magnetic field that induced the eddy currents
    C. Cancels the magnetic field that induced the eddy currents
    D. Has no effect on the magnetic field that induced the eddy currents
A

A. Oppose the magnetic fields that induce the eddy currents

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7
Q
  1. In eddy current testing, IACS is a recognized appreciation for:
    A. Induced Alternating Current System
    B. Inductively Activated Comparison System
    C. International Applied Current System
    D. International Annealed Copper Standard
A

D. International Annealed Copper Standard

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8
Q 
8. In eddy current testing, the specimen is coupled to the test coil by:
A. Core coupling
B. Magnetic saturation
C. The coil’s electromagnetic fields
D. Magnetic domains
A

C. The coil’s electromagnetic fields

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9
Q
  1. The penetration of eddy currents in a conductive material is decreased when the:
    A. Test frequency or conductivity of the specimen is decreased
    B. Test frequency is decreased or conductivity of the specimen is increased
    C. Test frequency, conductivity, or permeability is increased
    D. Permeability of the specimen is decreased
A

C. Test frequency, conductivity, or permeability is increased

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10
Q 
10. At a fixed test frequency, in which of the following materials will the eddy current penetration be greatest?
A. Aluminum (35% IACS conductivity)
B. Brass (15% IACS conductivity)
C. Copper (95% IACS conductivity)
D. Lead (7% IACS conductivity)
A

D. Lead (7% IACS conductivity)

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11
Q 
11. A term used to describe the effect observed due to a change in the coupling between a test specimen and a flat probe coil when the distance of separation between them is varied is:
A. Fill factor
B. Edge effect
C. End effect
D. Lift-off
A

D. Lift-off

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12
Q
  1. When testing with eddy currents, discontinuities will be most easily detected when the eddy currents are:
    A. Coplanar with the major dimension of the discontinuity
    B. Perpendicular to the major plane of the discontinuity
    C. Parallel to the major dimension of the discontinuity
    D. 90 degrees out of phase with th current in the coil
A

B. Perpendicular to the major plan of the discontinuity

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13
Q
  1. Which of the following discontinuities is easiest to detect with an eddy current test?
    A. A subsurface crack which lies parallel to the direction of the eddy current
    B. A discontinuity located in the center of a 2” diameter bar
    C. A radial crack that extends to the outer surface of a 2” diameter bar
    D. A subsurface radial crack located at a depth of 0.5” in a 2” diameter bar
A

C. A radial crack that extends to the outer surface of a 2” diameter bar

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14
Q 
14. A term used to define the timing relationships involved in alternating current signals is:
A. Magnitude
B. Phase
C. Impedance
D. Time-gain correction
A

B. Phase

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15
Q
  1. The impedance of a test coil can be represented by the vector sum of:
    A. Inductive reactance and resistance
    B. Capacitive reactance and resistance
    C. Inductive reactance and capacitive reactance
    D. Inductive reactance, capacitive reactance and resistance
A

A. Inductive reactance and resistance

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16
Q
  1. Disadvantages of using a surface probe coil for the eddy current inspection of small-diameter tubing include:
    A. Inability to detect small discontinuities
    B. Lift-off variations effect
    C. Inherent mechanical problems
    D. Slow inherent speed
A

B. Lift-off variations effect

17
Q 
17. The term “fill factor” applies to:
A. A surface coil
B. Coaxial cable
C. An encircling coil
D. The ability to null an eddy current instrument
A

C. An encircling coil

18
Q 
18. Which of the following materials would be more likely used as a mounting material for a probe coil?
A. Aluminum
B. Plastic
C. Copper
D. Non-ferromagnetic steel
A

B. Plastic

19
Q 
19. Which of the following is not a commonly used eddy current testing read-out mechanism:
A. Signal generator
B. Meter
C. Cathode Ray Tube (CRT)
D. Strip-chart recorder
A

A. Signal generator

20
Q
  1. Reference standards used for eddy current testing:
    A. Must contain artificial discontinuities such as notch’s and drilled holes
    B. Must contain natural discontinuities such as cracks and inclusions
    C. Must be free of measurable discontinuities, but may contain artificial or natural discontinuities or may be free of discontinuities depending on the test system and the type of test being conducted.
    D. Must be constructed from the same material as the object being inspected
A

D. Must be constructed from the same material as the object being inspected

21
Q
  1. Which of the following conditions is not important when selecting specimens to be used as reference standards:
    A. The specimen should be of the same size and shape as the test piece
    B. The specimen should be of the same materials and have the same heat treatment as the piece being tested
    C. The surface finish of the specimen should be the same as the piece to be tested
    D. If the material is aluminum, the surface should be anodized
A

D. If the material is aluminum, the surface should be anodized

22
Q
  1. Which of the following conditions would be the most difficult to detect when eddy current testing a rod using an encircling coil?
    A. A short surface crack that has a depth of 10% of the rod diameter
    B. A small inclusion in the center of the rod
    C. A 5% change in diameter
    D. A 10% change in conductivity
A

B. A small inclusion in the center of the rod

23
Q
  1. The thickness of non-conductive coatings on a conductive base can be most simply measured by:
    A. Observing the lift-off effect caused by the coating
    B. Testing both sides of the specimen
    C. Varying the test frequency over a given range during the test
    D. Using a specially shaped encircling coil
A

A. Observing the lift-off effect caused by the coating

24
Q 
24. Some of the products commonly tested using encircling coils are:
A. Rods, tubes, and wire
B. Interior of hollow tubes
C. Sheets and metal foil
D. Square billets and plates
A

A. Rods, tubes, and wire

25
Q
  1. It is often possible to sort various alloys of a non-magnetic metal by means of an eddy current test when:
    A. There is a unique range of permeability values for each alloy
    B. There is a unique range of conductivity values for each alloy
    C.The direction of induced eddy currents varies for each alloy
    D. The magnetic domains for each alloy are different
A

B. There is a unique range of conductivity values for each allow

26
Q 
26. When conducting eddy current testing on tubing with a system that includes a frequency discriminating circuit, which of the following variables would be declassified as a high frequency variable?
A. Small discontinities
B. Conductivity changes
C. Diameter changes
D. Wall thickness variations
A

A. Small discontinuities

27
Q
  1. Which of the following is not a candidate for testing by the eddy current method?
    A. A 4” thick plate to be tested for discontinuities throughout the plate
    B. Tubing to be tested for surface cracks
    C. A rod to be tested for laps and seams
    D. Tubing to be tested for variation in outside diameter
A

A. A 4” thick plate to be tested for discontinuities throughout the plate

ASNT Study Guide - Chapter 4 (11 decks)

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