Eddy Current Testing (ET) Level I Practice Test

These questions are part of the practice quiz. Start practicing

• What is a reference plane in ET testing?
• How can you distinguish a true material defect from a corrosion pit signal?
• Which term describes the clarity of separation between individual test signals as displayed by the instrument?
• What does lift-off refer to in eddy current testing?
• How does increasing lift-off generally affect the ET signal amplitude on a surface inspection?
• During testing, the secondary magnetic field developed by the eddy currents does what to the coil's field?
• Outline a typical calibration procedure for an ET Level I test.
• In eddy current testing, what is induced in the test coil as the magnetic field changes?
• Which factor best maintains baseline stability during repeated ET measurements on the same part?
• Calibration blocks in ET are used for what purpose?
• A tightly wound, or 'narrow' coil would most likely be used to detect which type of discontinuities?
• How is repeatability verified during calibration?
• How does the presence of a liquid layer on the surface affect ET readings?
• During eddy current testing, which phenomenon is generated in a conductor when it is exposed to a changing magnetic field?
• What is the primary purpose of labeling scans with lift-off and scanning conditions?
• What is the effect of increased lift-off on ET signals?
• Which material property tends to cause stronger lift-off effects and impedance changes in ET, ferrous or non-ferrous?
• Gauss is a unit used in magnetism to measure which physical quantity?
• What are typical pass/fail criteria in Level I ET practice?
• Opposition to current flow caused by induction of back voltage in a coil is called:
• What is the basic physical principle behind eddy current testing?
• Which statement about lift-off variations and sizing is most accurate?
• What is stand-off in ET and how is it measured?
• How do you size a defect from ET data using calibration?
• The conductivity of a material can be changed by changing the:
• How does material thickness interact with ET signal when a defect is near the surface?
• Which term describes the circuit type used to connect the coil in many ET instruments?
• What is the role of a calibration standard in ET Level I testing?
• Which steps comprise a typical ET calibration procedure using a reference standard?
• What is the purpose of establishing a lift-off baseline in ET?
• Why is impedance recorded at several lift-off values during ET calibration?
• Name the two material properties that most strongly influence an ET response and briefly state why.
• What best practices should be followed when recording ET data?
• As material conductivity increases, the impedance vector on the impedance plane tends to rotate toward the horizontal axis, indicating a decrease in which quantity?
• Residual magnetism is the amount of flux density remaining in the material after the magnetizing force has been removed
• One gauss is defined as one line of magnetic flux per which area?
• What is a common method to mitigate lift-off effects in ET measurements?
• In ET signal interpretation, how do surface defects differ from near-surface defects?
• On the impedance plane, the 'coil in air' point is located at a position of?
• What information does the phase angle provide about a flaw?
• Which term describes inducing current in a separate coil without direct electrical connection?
• What is the purpose of establishing a baseline in ET testing?
• The conductivity of a material can be changed by changing which of the following?
• IACS is a recognized abbreviation for:
• How should surface contaminants such as water or oil be handled before ET testing?
• What effect does surface roughness have on ET measurements?
• Which statement describes phase and amplitude analysis in ET?
• Which statement best describes data documentation in ET practice?
• How do non-conductive surface coatings affect ET signals?
• A term used to define a unit of flux density is:
• CGS unit for magnetic flux density is which?
• What is the purpose of lift-off compensation in ET testing?
• What is a typical signal feature used to indicate a through-wall defect on an impedance plane?
• Which coil configuration is used to evaluate the entire circumference of a test part at once in eddy current testing?
• What artifact is commonly produced by misaligned probes in ET, and how can it be mitigated?
• When inspecting curved surfaces, ET challenges include lift-off variation and alignment issues. Which approach helps mitigate these challenges?
• What is a bobbin (encircling) coil and when is it most appropriate to use it?
• What effect do friction and heat of eddy currents have on the display?
• How do ferromagnetic materials typically differ from non-ferrous metals in ET response?
• What is a typical consequence of poor grounding in ET instrumentation?
• Which expression represents Ohm's law for current in terms of voltage and resistance?
• What does the phase angle tell you in an ET signal, and how is it used?
• The region around a magnet that exerts magnetic forces on nearby magnetic materials is called the:
• What is the purpose of an impedance plane (Lissajous) display in ET?
• Why is thorough documentation of test conditions important in ET?
• The inductive reactance in a coil is out of phase with the coil's resistance by how many degrees?
• What is the difference between absolute and differential ET probes?
• Direct current saturation coils are commonly used for testing which class of materials?
• Relative motion between ______ and a conductor indirectly induces an electrical current flow in that conductor.
• Which material property primarily determines how strongly eddy currents are induced and how the probe impedance changes?
• What elements should be included in an ET Level I test plan?
• Which statement about ferrite-core probes is true?
• The principle, discovered by Faraday, whereby a primary coil can cause a voltage in a completely separate secondary coil is called:
• Which statement best describes the effect of higher material conductivity on defect-related impedance change in ET?
• The principle, discovered by Faraday, where a primary coil can induce current in a completely separate secondary coil is called:
• How does coating thickness influence flaw detection in ET?
• Which statement best describes the pancake/surface coil in ET?
• The phenomenon describing the leftover magnetism after magnetizing force is removed is
• Conductivity is inversely related to:
• What term describes the observed change when the distance between a surface coil and a test specimen is varied?
• Eddy currents are sensitive to which of the following material variables?
• Which element best describes data recording in an ET test plan?
• What factors are especially critical when inspecting aluminum with ET to obtain reliable results?
• The number of lines of flux in a unit area is defined as:
• Which statement best describes Ohm's law in simple terms?
• How does selecting different frequencies affect defect detection depth and sensitivity?
• When inspecting aluminum with ET, which factors are especially critical?
• Eddy currents are circulating electrical currents indirectly induced in an isolated conductor by which of the following?
• What safety considerations are essential for ET work?
• Why is calibration against standards necessary for ET?
• List common electrical noise sources in ET setups and how to mitigate them.
• When inspecting curved surfaces, which challenges arise for ET?
• When testing by the eddy current method, discontinuities will most easily be detected when the eddy currents are:
• Why is multi-frequency ET advantageous?
• The coil assembly in most eddy current instruments is connected through which type of circuit?
• Energy dissipation due to eddy currents is manifested as heat in which part of the system?
• How does frequency affect skin depth in ET, and what is the formula?
• How would a ferromagnetic coating on a steel part influence ET results?
• What is a key advantage of using a differential probe in ET?
• Define skin depth and provide the standard formula.
• A coil's magnetic field may be viewed as a distribution of lines of flux around the coil. The number of lines in a unit area is defined as:
• The primary advantage of using a shielded surface probe is to
• What is the significance of field calibration in Eddy Current Testing (ET)?
• What are the typical safety considerations for ET labs?
• Which statement describes the effect of defect orientation on ET signals?
• Which probe type is designed to suppress lift-off and enhance flaw signals?
• Higher test frequency in eddy current testing will generally cause the penetration depth to:
• Which coil type provides broad, uniform excitation ideal for tubes, pipes, or flat areas?
• How does temperature affect ET readings?
• What is lift-off calibration and why is it essential for repeatable measurements?
• What does using a defect-free reference with known geometry during calibration primarily enable?
• How does coil geometry influence sensitivity to defects at different depths?
• The inductive reactance in the coil is out of phase with the coil's resistance by:
• Which probe configuration is NOT commonly used in ET?
• IACS is a recognized abbreviation for what standard?
• What is a reference plane in ET testing, and why is it important?
• Increasing lift-off generally causes which effect on coil coupling?
• Which term represents the density of magnetic flux lines per unit area around a coil?
• Which property of ferromagnetic materials can distort ET signals compared to non-ferrous metals?
• Lift-off in eddy current testing is defined as what?
• Which defect types does ET detect most effectively?
• What is an impedance plane plot used for in ET data interpretation?
• What roles do grounding and shielding play in ET instrument reliability?
• The quantity defined as the number of magnetic flux lines per unit area around the coil is called:
• To detect very small surface discontinuities near the edge of features, which coil is typically preferred?
• The degree to which separation between test signals can be displayed refers to which parameter?
• Why might ET be used in the inspection of non-metallic-coated metallic objects?
• If a coating breach occurs, what is the typical effect on signals detected beneath the coating after a proper baseline has been established?
• Changes in the impedance of the test coil produce what kind of change on the impedance display?
• Why do ET procedures differ between ferrous and non-ferrous materials?
• What is a reference standard, and how is it used in ET?
• What is the name of the relationship between inductive reactance and resistance as defined by the angle between the impedance vector and the resistance axis?
• In ET impedance measurements, what does phase refer to?
• What is lift-off compensation and how is it implemented?
• What is the role of baseline subtraction in ET interpretation?
• What is the purpose of calibration blocks in ET inspections?
• How can probe wear or damage affect ET measurements?
• The major advantage as well as the primary weakness of the eddy current test method is that it is
• In an eddy current instrument, what occurs on the display when the coil impedance changes?
• Which term describes the phenomenon in which a changing magnetic flux through a coil induces voltage in a secondary coil?
• In a tube inspection, what defect modes are commonly sought?
• What is the effect of lift-off and how can it be managed during ET testing?
• How can temperature affect ET measurements?
• What is a key difference between surface-breaking and near-surface flaws in ET signals?
• How can you differentiate between a real defect and a lift-off artifact during ET data interpretation?
• What is a baseline reference in ET and how is it used?
• What is the practical benefit of recording impedance at multiple lift-off distances during calibration?
• Which of the following is NOT a common strategy to compensate lift-off effects during ET testing?
• What term describes the overall opposition to current flow in the eddy current test coil?
• The depth at which eddy current density decays to about 36.8% of the surface value is known as
• Why might a ferromagnetic coating require specialized calibration in ET?
• The current that continually reverses direction is described as
• To generate measurable eddy currents in a test specimen, the specimen must be:
• In ET, what indicates a flaw in the material?
• How does increasing lift-off generally affect the eddy current signal amplitude for a fixed defect?
• The term fill factor applies to which type of probes in eddy current testing?
• Outline a simple ET inspection procedure for a flat plate with a known surface crack.
• How does probe orientation relative to defect features influence ET signals?
• What term describes the depth at which eddy current density decreases to about 36.8% of the surface value?
• In an eddy current test, what is the result of the coil's changing magnetic field in the coil's circuit?
• How would you differentiate a true crack signal from a lift-off artifact when scanning with multi-frequency ET?
• What is induced in eddy current test coils as a result of the coil's changing magnetic field?
• Why is it important to perform multi-frequency testing in ET?
• Eddy currents circulating in the test material dissipate energy primarily as which form?
• Which configuration is typically used for inspections where access is from only one side and surface contact is limited?
• How does material thickness interact with ET signal when a near-surface defect is involved?
• Why is proper probe handling important for repeatable ET results?
• When using an internal coil ET probe, what defect types are you most likely to detect?
• Why is on-site calibration important?
• "coil in air" point is located on the impedance plane at a position of which combination?
• Why is temperature compensation or recalibration often required in ET testing?
• A term used to define a unit of flux density is
• What is a lift-off baseline in ET?
• How are ET data typically recorded and documented for QA?
• For the same defect, how does increased material conductivity affect the ET signal amplitude?
• Which statement best describes the role of ferrite-core probes in ET?
• Relative motion between an AC magnetic field and a conductor in that field induces ______ into that conductor.
• In impedance plane analysis, the movement of the impedance trace usually correlates with what property of a crack-like defect?
• Which probe configuration is typically used for internal or immersion ET testing?
• What is an internal coil ET probe, and when would you use it?
• Which statement describes lift-off artifacts in ET?
• Which of the following is NOT typically recorded as a parametric data point in ET inspections?
• List three common probe types used in ET and give a brief use case for each.
• Direct and indirect measurements differ in ET data interpretation.
• The Gauss is a term used to define a unit of what quantity?
• How does flaw orientation relative to the probe affect ET signals?
• Which practice is primarily used to account for lift-off when testing multiple parts with varying gaps?
• A magnetic field around a coil may be viewed as a distribution of lines of flux around the coil. The number of lines per unit area is defined as:
• What role do reference standards play in ET evaluation?
• Why is probe geometry important in ET?
• What is meant by lift-off compensation in instrumentation?
• What is the consequence of poor probe handling in ET inspections?
• If a test requires monitoring the entire circumference of a part in a single reading, which coil type is most appropriate?
• In the impedance plane, what is a typical indicator of a crack-like defect?
• 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 which electrical device?
• An AC current flowing in a conductor will set up which of the following?
• If an impedance plane trace shifts horizontally with little vertical movement, what might this indicate?
• What is induced in eddy current coils as a result of the coil's changing magnetic field?
• The property describing how easily a ferromagnetic material can be magnetized is called:
• What is a differential probe used for in ET?
• Saturated ferromagnetic materials can retain magnetism after removing the external magnetizing field. This remaining magnetism is called:
• Which routine checks should be performed on ET equipment before an inspection?
• What term describes the effect observed when the distance between a test specimen and a surface coil is varied and the electromagnetic coupling changes?
• On an impedance plane, how does a crack usually appear compared with a corrosion feature?
• The thickness of paint and other nondestructive coatings on metallic surfaces may be measured by which method?
• If the current flowing through the coil is alternating, the magnetic field will
• The region around a magnet which attracts other pieces of iron or steel is called the:
• In eddy current measurements, the property that is out of phase with resistance is called:
• What is the general limitation of ET when inspecting thick materials?
• Which factor is primarily responsible for drift of the display in eddy current testing?
• Which expression correctly solves for current using voltage and resistance?
• In Ohm's law, if voltage doubles while resistance remains the same, what happens to current?
• Why is it important to record lift-off in ET data logs?
• Some of the products commonly tested using encircling coils are:
• If inductive reactance decreases while resistance remains constant, the impedance phase angle will become:
• What does probe compensation in ET aim to adjust?
• Provide a generic acceptance criterion for a Level I surface crack in a test block.
• Why is it beneficial to compare measurements from multiple probe geometries in ET?
• Which probe configuration is typically used to inspect tube internals?
• An eddy current test coil's total opposition to the flow of current is called what?
• Which of the following is typically included in the parametric data points recorded during ET inspections?
• Direct current saturation coils would most likely be used when testing which material?
• Which test frequency would produce eddy currents with the least depth of penetration?
• How does changing frequency affect depth of penetration in ET?
• How does high magnetic permeability influence ET signals in ferrous vs non-ferrous metals?
• Which approach best distinguishes gap-type defects from through-wall defects in eddy current testing?
• What is the effect of conductivity on how eddy currents are induced in ET?
• What is the basic physical principle behind eddy current testing?
• What are the two components of eddy current impedance, and how do eddy currents affect them?
• As test material conductivity increases, what happens to the coil's inductive reactance?
• Which instrument setting adjustments help detect shallow defects without excessive lift-off impact?
• What strategy helps validate pit-specific signals when inspecting for pits or corrosion?
• What is the primary electrical quantity measured in eddy current testing?
• What is a pencil probe typically used for?
• Which method helps reliably detect changes in lift-off during an ET scan?
• An eddy current test coil's combined opposition to the flow of current is called:
• What is the purpose of a baseline reference in ET data interpretation?
• Back voltage in eddy current testing is produced by which phenomenon?