A Trivia Quiz On Magnetic Particle Testing!

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  • 1/62 Questions

    An electric current which flows steadily in one direction is:

    • Direct current
    • Full wave current
    • Half wave current
    • Alternating current
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About This Quiz

Magnets have been used for a long time as a way to check steel components on production lines using a specific measure. Below is a trivia quiz on magnetic particle testing designed to help you see how well you understand the method as a whole. How about you check it out and get to refresh your understanding. All the best!

A Trivia Quiz On Magnetic Particle Testing! - Quiz

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  • 2. 

    In the inspection of a part, the following may justify rejection of some parts:

    • Inherent defects

    • Service defects

    • Processing defects

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    All of the above may justify the rejection of some parts in the inspection of a part. Inherent defects refer to flaws or imperfections that are present in the part from the beginning, such as structural weaknesses or material defects. Service defects are defects that occur during the part's use or service, such as wear and tear or damage caused by external factors. Processing defects are defects that occur during the manufacturing or processing of the part, such as errors in production or assembly. Therefore, any of these defects can be valid reasons for rejecting parts during inspection.

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  • 3. 

    The point at which the magnetism in a material cannot be increased even though the magnetizing force continues to increase is known as the:

    • Salient pole.

    • Saturation point.

    • Residual point.

    • Remnant point.

    Correct Answer
    A. Saturation point.
    Explanation
    The saturation point is the point at which the magnetism in a material cannot be increased even though the magnetizing force continues to increase. At this point, the material is fully magnetized and any additional increase in the magnetizing force will not result in a further increase in magnetism.

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  • 4. 

    If a crack exists in a circular magnet, the attraction of magnetic particles to the crack is caused by the:

    • Coercive force

    • Leakage field

    • Doppler effect

    • High reluctance at the crack

    Correct Answer
    A. Leakage field
    Explanation
    The attraction of magnetic particles to a crack in a circular magnet is caused by the leakage field. When there is a crack in the magnet, the magnetic field lines tend to concentrate at the crack, creating a leakage field. This leakage field attracts magnetic particles towards the crack, allowing for the detection of the crack using magnetic particle inspection techniques.

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  • 5. 

    The areas on a magnetized part from which the magnetic field is leaving and entering the part are called:

    • Salient points

    • Discontinuities

    • Magnetic poles

    • Nodes

    Correct Answer
    A. Magnetic poles
    Explanation
    The areas on a magnetized part where the magnetic field is leaving and entering the part are called magnetic poles. Magnetic poles are the regions where the magnetic field lines originate (north pole) or terminate (south pole). These poles are responsible for the attraction or repulsion between magnets and are essential in understanding the behavior of magnetic materials.

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  • 6. 

    A part is adaptable to magnetic particle testing if:

    • It is attached to an electrostatic field

    • The material is ferromagnetic

    • The material is nonferrous

    • The material is an electric conductor

    Correct Answer
    A. The material is ferromagnetic
    Explanation
    The correct answer is that the material is ferromagnetic. Ferromagnetic materials have the ability to become magnetized when exposed to a magnetic field, making them suitable for magnetic particle testing. This testing method involves applying a magnetic field to the material and then applying magnetic particles to the surface. If there are any defects or cracks in the material, the particles will be attracted to them, making them visible and allowing for inspection.

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  • 7. 

    Hysteresis loops and the magnetic properties of materials may be affected by:

    • Grain size

    • Microstructure

    • Chemical composition

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    Hysteresis loops and magnetic properties of materials can be influenced by various factors including grain size, microstructure, and chemical composition. Grain size refers to the size of individual crystals in a material, and it can affect the movement of magnetic domains within the material. Microstructure refers to the arrangement and distribution of different phases or constituents in a material, and it can impact the magnetic behavior. Chemical composition refers to the elements and their proportions present in a material, which can alter its magnetic properties. Therefore, all of these factors can have an impact on hysteresis loops and magnetic properties.

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  • 8. 

    The lines of magnetic flux within and surrounding a magnetized part or around a conductor carrying current is known as:

    • Saturation lines

    • Magnetic field

    • Ferromagnetic rays

    • Coercive lines

    Correct Answer
    A. Magnetic field
    Explanation
    The lines of magnetic flux within and surrounding a magnetized part or around a conductor carrying current are known as the magnetic field. The magnetic field is a region in which magnetic forces can be detected and is represented by the direction and strength of the magnetic lines of force. It is responsible for the attractive or repulsive forces between magnets and the interaction between magnets and electric currents.

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  • 9. 

    A curve is sometimes drawn to show graphically the relationship of the magnetizing force to the strength of the magnetic field produced in a material. This is known as the:

    • Magnetic force curve

    • Hysteresis curve

    • Saturation curve

    • Induction curve

    Correct Answer
    A. Hysteresis curve
    Explanation
    A hysteresis curve is a graphical representation that shows the relationship between the magnetizing force and the strength of the magnetic field produced in a material. It is called a hysteresis curve because it illustrates the phenomenon of hysteresis, which refers to the lagging of the magnetic field behind the magnetizing force. This curve is important in understanding the magnetic properties of materials and is commonly used in the study of magnetic materials and devices.

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  • 10. 

    A magnetic particle build-up from a discontinuity is strongest when the discontinuity is oriented:

    • 180° to the magnetic field.

    • 45° to the magnetic field.

    • 90° to the magnetic field.

    • 90° to the current flow.

    Correct Answer
    A. 90° to the magnetic field.
    Explanation
    When a discontinuity is oriented 90 degrees to the magnetic field, it creates a stronger magnetic particle build-up. This is because the magnetic field lines are perpendicular to the discontinuity, resulting in a greater concentration of magnetic particles at the discontinuity. When the discontinuity is oriented at other angles, the magnetic field lines and the discontinuity are not perpendicular, leading to a weaker magnetic particle build-up. Therefore, the strongest magnetic particle build-up occurs when the discontinuity is oriented 90 degrees to the magnetic field.

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  • 11. 

    The permeability of a material describes:

    • The ease with which it can be magnetized

    • The depth of the magnetic field in the part

    • The length of time required to demagnetized it

    • The ability to retain the magnetic field

    Correct Answer
    A. The ease with which it can be magnetized
    Explanation
    The permeability of a material refers to its ability to allow the passage of magnetic lines of force. It describes the ease with which the material can be magnetized, meaning how easily it can become magnetized when exposed to a magnetic field. A high permeability material can be easily magnetized, while a low permeability material resists magnetization. Therefore, the correct answer is "the ease with which it can be magnetized".

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  • 12. 

    In a ferromagnetic material, a region where all the atomic moments are aligned parallel to each other is called a:

    • Magnetic zone

    • Confederation

    • Domain

    • Magnetic junta

    Correct Answer
    A. Domain
    Explanation
    In a ferromagnetic material, a region where all the atomic moments are aligned parallel to each other is called a domain. This term refers to a small region within the material where the magnetic moments of the atoms are aligned in the same direction, creating a strong magnetic field. These domains contribute to the overall magnetization of the material.

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  • 13. 

    When the central conductor MPI method is used to inspect a ring shaped object, or short cylinder:

    • Only inside diameter surface flaws can be found

    • Only outside diameter surface flaws can be found

    • Both inside and outside surface and subsurface flaws can be found if the wall thickness is not too great

    • None of the above, central conductors cannot be used for ring shaped objects

    Correct Answer
    A. Both inside and outside surface and subsurface flaws can be found if the wall thickness is not too great
    Explanation
    The central conductor MPI method is capable of detecting both inside and outside surface flaws as well as subsurface flaws in a ring-shaped object or short cylinder, as long as the wall thickness is not too great. This method involves passing an electric current through the central conductor, creating a magnetic field that can reveal any flaws or defects in the material. The magnetic field interacts differently with different types of flaws, allowing for their detection. Therefore, this method is effective in identifying various types of flaws in ring-shaped objects.

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  • 14. 

    Based on the domain theory, an unmagnetized part has domains that are:

    • Randomly oriented

    • Aligned north to south

    • Aligned east to west

    • Aligned 90 degrees to the current flow

    Correct Answer
    A. Randomly oriented
    Explanation
    Based on the domain theory, an unmagnetized part has randomly oriented domains. This means that the magnetic domains within the part are not aligned in any specific direction. This lack of alignment results in the absence of a magnetic field or magnetization in the part.

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  • 15. 

    Of the four sources of magnetism, which one is most often used in magnetic particle testing?

    • The Earth's field

    • Permanent magnets

    • Mechanically-induced magnetism

    • Electrically-induced magnetism

    Correct Answer
    A. Electrically-induced magnetism
    Explanation
    Electrically-induced magnetism is the most often used source of magnetism in magnetic particle testing. This is because electrically-induced magnetism allows for greater control and manipulation of the magnetic field, making it easier to detect and analyze magnetic particles. Permanent magnets, mechanically-induced magnetism, and the Earth's field may also be used in certain cases, but electrically-induced magnetism is the preferred choice due to its versatility and reliability in magnetic particle testing.

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  • 16. 

    What equipment is used to determine if a part has been demagnetized?

    • A pie gauge

    • A multimeter

    • A field indicator

    • Two paper clips held close to the part

    Correct Answer
    A. A field indicator
    Explanation
    A field indicator is used to determine if a part has been demagnetized. A field indicator is a device that can detect the presence or absence of a magnetic field. It is commonly used in industries where demagnetization is important, such as manufacturing or electronics. By using a field indicator, technicians can assess whether a part has been successfully demagnetized by checking for the absence of any magnetic field. This helps ensure that the part is free from any unwanted magnetism that could affect its performance or interfere with other components.

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  • 17. 

    The flux density of the magnetism induced by a coil can be controlled by varying:

    • The coil size

    • The current in the coil

    • The number of turns in the coil

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    The flux density of the magnetism induced by a coil can be controlled by varying the coil size, the current in the coil, and the number of turns in the coil. The size of the coil affects the amount of magnetic field generated, with a larger coil producing a stronger field. The current flowing through the coil also influences the strength of the magnetic field, as a higher current results in a stronger field. Additionally, increasing the number of turns in the coil increases the magnetic field strength. Therefore, all of the above factors can be adjusted to control the flux density of the magnetism induced by a coil.

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  • 18. 

    The negative magnetizing force required to reduce the residual flux density in a part to zero after saturation is called:

    • Residual force

    • Coercive force

    • Demagnetizing field strength

    • Null force 

    Correct Answer
    A. Coercive force
    Explanation
    The coercive force is the negative magnetizing force required to reduce the residual flux density in a part to zero after saturation. This force is necessary to demagnetize the material and bring it back to its original state. It is called "coercive" because it represents the ability of a material to resist changes in its magnetic state. The coercive force is an important parameter in understanding the magnetic properties of a material and is often used in the design and analysis of magnetic devices.

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  • 19. 

    The ampere turns for inducing a longitudinal field has been determined to be 15,000 ampere turns. If the stationary unit's coil has five windings, what amperage should the unit be set for to properly magnetize the part?

    • 3000 A

    • 5000 A

    • 7500 A

    • 15,000 A

    Correct Answer
    A. 3000 A
    Explanation
    The ampere turns for inducing a longitudinal field is determined to be 15,000 ampere turns. The stationary unit's coil has five windings. To properly magnetize the part, the amperage should be set for 3000 A.

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  • 20. 

    Which type of magnetic field produces a readily detectable north and south pole in a part?

    • Circular

    • Longitudinal

    • Circular when a central conductor is used

    • Circular when a headshot is used

    Correct Answer
    A. Longitudinal
    Explanation
    A longitudinal magnetic field produces a readily detectable north and south pole in a part. In a longitudinal magnetic field, the magnetic field lines run parallel to the direction of the current flow. This type of field can easily be detected using a compass or other magnetic field detection devices, as the north and south poles are clearly defined. Circular magnetic fields, on the other hand, do not have distinct north and south poles, making them less detectable. The options mentioning circular magnetic fields are therefore incorrect.

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  • 21. 

    A subsurface discontinuity can be detected by magnetic particle testing. What factor limits the ability to detect subsurface discontinuities?

    • The type of material being tested

    • The geometry of the part being tested

    • The type of current and particle medium used

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    The ability to detect subsurface discontinuities in magnetic particle testing is limited by the type of material being tested, the geometry of the part being tested, and the type of current and particle medium used. The type of material can affect the magnetic properties and the ability of the particles to adhere to the surface. The geometry of the part can affect the accessibility of the surface for testing. The type of current and particle medium used can also influence the sensitivity and effectiveness of the testing method.

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  • 22. 

    The value of H applied to bring the residual value of B to zero is called:

    • Saturation field

    • Demagnetization value

    • Coercive force

    • Phase reversal factor

    Correct Answer
    A. Coercive force
    Explanation
    The coercive force refers to the amount of magnetic field strength required to reduce the residual magnetism in a material to zero. It is the measure of a material's ability to resist demagnetization. In this context, when the value of H (magnetic field strength) is applied to bring the residual value of B (magnetic induction) to zero, it is referred to as the coercive force.

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  • 23. 

    A void in an otherwise homogenous magnetized material presents itself as a point magnetic dipole. This is the basis for:

    • Magnetic particle flaw detection

    • Multi frequency eddy current

    • Para-magnetism

    • De-magnetization

    Correct Answer
    A. Magnetic particle flaw detection
    Explanation
    When a void, or defect, is present in a magnetized material, it disrupts the homogeneity of the magnetic field and creates a point magnetic dipole. This means that the magnetic field is concentrated at the location of the void. Magnetic particle flaw detection takes advantage of this by using magnetic particles that are attracted to and accumulate around the void, making it visible and detectable. This technique is commonly used in industries such as manufacturing and engineering to identify defects or flaws in materials.

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  • 24. 

    The most important characteristic(s) that a dry powder should have is/are:

    • Low coercive force

    • Low magnetic retentivity

    • High magnetic permeability

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    A dry powder should have low coercive force, low magnetic retentivity, and high magnetic permeability. Low coercive force means that the powder can be easily magnetized and demagnetized. Low magnetic retentivity ensures that the powder does not retain a magnetic field after being magnetized. High magnetic permeability allows the powder to efficiently conduct magnetic flux. Therefore, all of these characteristics are important for a dry powder to effectively function in magnetic applications.

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  • 25. 

    The magnitude of the residual magnetic field in a specimen is dependent on:

    • The length to diameter ratio

    • The strength of the applied magnetizing force

    • The right hand rule

    • The left hand rule

    Correct Answer
    A. The strength of the applied magnetizing force
    Explanation
    The magnitude of the residual magnetic field in a specimen is dependent on the strength of the applied magnetizing force. This means that the stronger the magnetizing force applied to the specimen, the greater the residual magnetic field will be. The length to diameter ratio, the right hand rule, and the left hand rule are not directly related to the magnitude of the residual magnetic field.

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  • 26. 

    Alternating current produces a magnetic field in a part that has a better sensitivity to detect:

    • Surface discontinuities

    • Subsurface discontinuities

    • Surface and subsurface discontinuities

    • None of the above

    Correct Answer
    A. Surface discontinuities
    Explanation
    Alternating current produces a magnetic field that is primarily confined to the surface of a material. This magnetic field is better suited for detecting surface discontinuities, such as cracks or defects on the surface of a material. Subsurface discontinuities, on the other hand, may require other testing methods, such as ultrasonic or radiographic testing, which can penetrate deeper into the material to detect flaws beneath the surface. Therefore, the correct answer is surface discontinuities.

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  • 27. 

    What will be the result if a bath concentration is too high?

    • The testing amperage will have to be reduced to prevent masking of indications 

    • The testing amperage will have to be increased to ensure adequate flux leakage to attract the additional particles

    • The part will have to drain longer to reveal all indications

    • Discontinuities may be missed due to the masking of indications

    Correct Answer
    A. Discontinuities may be missed due to the masking of indications
    Explanation
    If the bath concentration is too high, it means that there is an excessive amount of particles or substances in the bath solution. This can lead to a situation where the indications or defects in the part being tested are masked or hidden by the excessive particles in the bath. As a result, the discontinuities or flaws in the part may not be easily detected or may be missed altogether. Therefore, the correct answer is that discontinuities may be missed due to the masking of indications.

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  • 28. 

    The opposition to the formation of a magnetic flux in a magnetic circuit is referred to as:

    • Reactance

    • Reluctance

    • Resistance

    • Antimagnetics

    Correct Answer
    A. Reluctance
    Explanation
    Reluctance is the opposition to the formation of a magnetic flux in a magnetic circuit. It is similar to resistance in an electrical circuit, where it hinders the flow of current. Reluctance depends on the material properties and geometry of the magnetic circuit. It is measured in units of ampere-turns per weber (A-turns/Wb). Reactance, on the other hand, refers to the opposition to the flow of alternating current in an electrical circuit due to inductance or capacitance. Resistance is the opposition to the flow of direct current in an electrical circuit. Antimagnetics is not a recognized term in the context of magnetic circuits.

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  • 29. 

    To reduce the discomfort of eye fatigue when performing fluorescent MPI you can:

    • Take breaks at regular intervals

    • Wear yellow-green tinted glasses (of the appropriate filtering ability)

    • Both a and b

    • Increase dark adaption time

    Correct Answer
    A. Both a and b
    Explanation
    Taking breaks at regular intervals and wearing yellow-green tinted glasses (of the appropriate filtering ability) can both help reduce the discomfort of eye fatigue when performing fluorescent MPI. By taking breaks, the eyes are given a chance to rest and recover, reducing strain and fatigue. Wearing yellow-green tinted glasses can help filter out certain wavelengths of light that can cause eye strain and fatigue. Therefore, both options can be effective in reducing eye fatigue during fluorescent MPI.

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  • 30. 

    How is half wave direct current created?

    • By alternating applications of power

    • By transforming alternating current

    • By rectifying alternating current

    • None of the above

    Correct Answer
    A. By rectifying alternating current
    Explanation
    Half wave direct current is created by rectifying alternating current. Rectification is the process of converting alternating current (AC) into direct current (DC) by allowing current to flow in only one direction. In the case of half wave rectification, only one half of the AC waveform is allowed to pass through, resulting in a pulsating DC waveform with current flowing in one direction.

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  • 31. 

    Magnetic lines of force are:

    • Isolated mono-poles

    • Elongated bi-poles

    • Manifestations of the "string-theory"

    • Imaginary concepts for mapping magnetic fields

    Correct Answer
    A. Imaginary concepts for mapping magnetic fields
    Explanation
    Magnetic lines of force are not physical entities but rather a conceptual tool used to visualize and map magnetic fields. They represent the direction and strength of the magnetic field at different points in space. These lines are imaginary and do not actually exist as physical lines. Instead, they provide a way to understand and describe the behavior of magnetic fields.

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  • 32. 

    Nonrelevant indications due to residual local poles interfere with magnetic particle testing. For a successful examination one should?

    • Magnetize in another direction

    • Demagnetize then remagnetize in the desired direction

    • Use lower amperage

    • Use more amperage

    Correct Answer
    A. Demagnetize then remagnetize in the desired direction
    Explanation
    Residual local poles can cause nonrelevant indications during magnetic particle testing. To overcome this interference, it is necessary to demagnetize the object first to remove any residual magnetism. After demagnetization, the object should be remagnetized in the desired direction to ensure a successful examination.

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  • 33. 

    What is a major advantage of dry visible particles over wet fluorescent particles?

    • They come in only one colour

    • They are more sensitive to small stress cracks

    • They do not require an ultraviolet light or darkened area

    • All of the above

    Correct Answer
    A. They do not require an ultraviolet light or darkened area
    Explanation
    Dry visible particles have a major advantage over wet fluorescent particles because they do not require an ultraviolet light or darkened area. This means that they can be easily used in any lighting condition, making them more convenient and accessible for inspections. Wet fluorescent particles, on the other hand, require specific lighting conditions to be visible, which can be more restrictive and time-consuming. Therefore, the fact that dry visible particles do not require special lighting makes them a preferred choice in many applications.

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  • 34. 

    Circular magnetism can be induced in a material by:

    • Headshot

    • Prods

    • Central conductor method

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    Circular magnetism can be induced in a material through various methods, including headshot, prods, and the central conductor method. These methods involve applying external forces or currents to the material, which results in the generation of a circular magnetic field. Therefore, the correct answer is "all of the above" as all the mentioned methods can induce circular magnetism in a material.

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  • 35. 

    A nonrelevant indication which can occur when the surface of a magnetized object comes in contact with another piece of ferromagnetic material or a current-carrying cable is:

    • Mechanical damage

    • Coercive lines of flux

    • Magnetic writing

    • None of the above

    Correct Answer
    A. Magnetic writing
    Explanation
    Magnetic writing refers to the phenomenon where the surface of a magnetized object leaves a temporary magnetic imprint on another piece of ferromagnetic material or a current-carrying cable when they come in contact. This can occur even without any intention of writing or leaving a mark. It is a nonrelevant indication because it does not cause any mechanical damage or involve coercive lines of flux.

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  • 36. 

    When welds are required to have only partial penetration, use of HWDC yokes often give rise to nonrelevant indications. This problem can be eliminated by:

    • Using an A.C. yoke

    • Increasing leg spacing

    • Reducing magnetizing current

    • Using a pie gage

    Correct Answer
    A. Using an A.C. yoke
    Explanation
    When welds are required to have only partial penetration, the use of HWDC (Half Wave Direct Current) yokes can often result in nonrelevant indications. This means that the yoke may detect flaws or indications that are not actually relevant or significant to the weld being inspected. To eliminate this problem, it is recommended to use an A.C. (Alternating Current) yoke instead.

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  • 37. 

    The width of a magnetic particle indication:

    • Indicates flaw depth

    • Is always wider than the actual flaw opening

    • Is equal to the height of particle indication

    • Is determined by the angle of repose

    Correct Answer
    A. Is always wider than the actual flaw opening
    Explanation
    The width of a magnetic particle indication is always wider than the actual flaw opening. This means that the indication of a flaw on a magnetic particle inspection will appear larger than the actual size of the flaw. This is because the magnetic particles tend to spread out and form a wider indication due to various factors such as the magnetic field, the type of particles used, and the surface tension of the liquid suspension. Therefore, it is important for inspectors to consider this when interpreting the indications and determining the severity of the flaws.

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  • 38. 

    Materials that are weakly attracted magnetically are called:

    • Paramagnetic 

    • Diamagnetic

    • Ferromagnetic

    • Nonmagnetic

    Correct Answer
    A. Paramagnetic 
    Explanation
    Paramagnetic materials are weakly attracted to a magnetic field due to the presence of unpaired electrons in their atomic or molecular orbitals. These materials become magnetized in the presence of a magnetic field but lose their magnetism once the field is removed. Diamagnetic materials, on the other hand, are weakly repelled by a magnetic field and do not retain any magnetism. Ferromagnetic materials have a strong attraction to a magnetic field and can retain their magnetism even after the field is removed. Nonmagnetic materials do not have any attraction or repulsion towards a magnetic field. Therefore, the correct answer is paramagnetic.

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  • 39. 

    The end of the magnet at which the lines are thought of as entering the bar is:

    • The north pole

    • The south pole

    • Both north and south poles

    • None of the above

    Correct Answer
    A. The south pole
    Explanation
    The end of the magnet where the lines are thought of as entering the bar is the south pole. This is because magnetic field lines always flow from the north pole to the south pole.

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  • 40. 

    Of the following discontinuity categories, which one is considered most detrimental to the service life of an item?

    • Subsurface inclusions

    • Subsurface porosity and voids

    • Cracks open to the surface

    • All of the above

    Correct Answer
    A. Cracks open to the surface
    Explanation
    Cracks that are open to the surface are considered the most detrimental to the service life of an item because they provide direct pathways for external elements such as moisture, chemicals, and contaminants to penetrate into the material. This can lead to accelerated corrosion, degradation, and structural failure, significantly reducing the lifespan of the item. Subsurface inclusions and porosity may also affect the integrity of the material, but they do not directly expose the material to external factors like cracks open to the surface do.

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  • 41. 

    Longitudinal magnetism is induced in a material by:

    • Headshot 

    • Coil

    • A yoke

    • Both b and c

    • All of the above

    Correct Answer
    A. Both b and c
    Explanation
    Longitudinal magnetism refers to the alignment of magnetic domains within a material along its length. This type of magnetism can be induced by both a coil and a yoke. A coil produces a magnetic field when an electric current flows through it, while a yoke is a magnetic circuit that helps to guide and concentrate the magnetic field. Therefore, both the coil and the yoke can contribute to the induction of longitudinal magnetism in a material. Hence, the correct answer is "both b and c" (coil and yoke).

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  • 42. 

    Magnetic flux lines that are parallel to a discontinuity produce:

    • Strong indications

    • Weak indications

    • No indications

    • Fuzzy indications

    Correct Answer
    A. No indications
    Explanation
    When magnetic flux lines are parallel to a discontinuity, they do not interact with the boundary and therefore do not produce any indications. This is because the flux lines are not crossing the boundary, resulting in no change in the magnetic field and no detection of the discontinuity.

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  • 43. 

    Which type of material would have the greatest resistance to demagnetization?

    • A part made of soft steel

    • A part made of hard steel

    • The resistance would be the same regardless of the material

    • The resistance to demagnetization is dependent on the type of field established in the part

    Correct Answer
    A. A part made of hard steel
    Explanation
    The correct answer is a part made of hard steel. Hard steel has a higher resistance to demagnetization compared to soft steel because it has a higher coercivity. Coercivity is the ability of a material to resist changes in its magnetization state, and materials with higher coercivity are more resistant to demagnetization. Therefore, a part made of hard steel would have the greatest resistance to demagnetization.

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  • 44. 

    The strength of a circular magnetic field is not determined by the  ________ of a part:

    • Permeability

    • Diameter

    • Length

    • Any of the above

    Correct Answer
    A. Length
    Explanation
    The strength of a circular magnetic field is not determined by the length of a part. The strength of a magnetic field is determined by factors such as the permeability of the material and the diameter of the part. The length of the part does not have a direct impact on the strength of the magnetic field.

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  • 45. 

    A hollow part's geometry would require what type of magnetic particle test to detect longitudinal stress cracks on the inner surface?

    • Circular magnetism applied with a head shot

    • Circular magnetism applied with a central conductor

    • Longitudinal magnetism applied with a head shot

    • Longitudinal magnetism applied with a central conductor

    Correct Answer
    A. Circular magnetism applied with a central conductor
    Explanation
    To detect longitudinal stress cracks on the inner surface of a hollow part, a magnetic particle test using circular magnetism applied with a central conductor is required. This method allows the magnetic particles to flow in a circular pattern around the central conductor, making it easier to detect any cracks or defects on the inner surface of the hollow part. Applying circular magnetism with a head shot or longitudinal magnetism would not be as effective in detecting longitudinal stress cracks on the inner surface.

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  • 46. 

    When it is necessary to achieve the greatest amount of demagnetization of a part, in what direction should the demagnetization coil be positioned?

    • East-west

    • North-south

    • North-east

    • South-west

    Correct Answer
    A. East-west
    Explanation
    The demagnetization coil should be positioned in the east-west direction in order to achieve the greatest amount of demagnetization of a part. This is because the magnetic field lines produced by the coil will intersect the magnetic field lines of the part at a perpendicular angle, resulting in a more effective demagnetization process.

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  • 47. 

    What effect does the length of the part have in determining the correct amperage to induce a circular magnetic field?

    • As the length increases, the amperage must increase

    • As the length decreases, the amperage can be decreased

    • The length does not have any effect on the required amperage

    • The length is restricted to ensure a ratio between 2 and 15

    Correct Answer
    A. The length does not have any effect on the required amperage
    Explanation
    The length of the part does not have any effect on the required amperage. The correct amperage to induce a circular magnetic field is not dependent on the length of the part.

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  • 48. 

    To ensure the inside of a hollow part is properly tested for lengthwise discontinuities, the part should be magnetized by:

    • Passing current through the part

    • Placing the part in a coil

    • Passing current through a central conductor

    • Any of the above would provide satisfactory results

    Correct Answer
    A. Passing current through a central conductor
    Explanation
    Passing current through a central conductor is the correct answer because this method allows for the magnetization of the entire hollow part, ensuring that all lengthwise discontinuities can be properly tested. By passing current through a central conductor, a magnetic field is generated that permeates the entire part, making it possible to detect any potential defects or discontinuities along its length. This method is effective in ensuring comprehensive testing of the hollow part for lengthwise defects.

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  • 49. 

    What is the major limitation of using alternating current for demagnetization?

    • It requires large amounts of electricity and therefore is not economical

    • It is only effective on steel parts

    • It is limited in its ability to remove deep magnetic fields

    • Alternating current does not have any limitations

    Correct Answer
    A. It is limited in its ability to remove deep magnetic fields
    Explanation
    The major limitation of using alternating current for demagnetization is that it is limited in its ability to remove deep magnetic fields. This means that it may not be effective in completely demagnetizing objects with strong or deep magnetic fields.

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Matt Balanda |BS (Aerospace Engineering) |
Science Teacher
Matt Balanda, a Calvary Chapel Christian School leader with a Bachelor's in Aerospace Engineering and Mathematics, transitioned from Aerospace Engineering to Education with a Master's from California Baptist University. As the High School Vice-Principal and Physics teacher, he nurtures students' love of learning and faith, creating an enriching and transformational educational experience.

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  • Oct 04, 2024
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