Magnetic Particle Testing Flashcards by Andrew McTaggart

Ferromagnetic material is:

a. strongly attracted by a magnet
b. capable of being magnetized
c. both A and B
d. not capable of being magnetized

c. both a and b

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The retentivity of a material describes the:

a. ease with which it can be magnetized
b. depth of the magnetic field in the part
c. length of time required to demagnetize it.
d. ability to retain the magnetic field

d. ability to retain the magnetic field

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Which of the following can be magnetized?

a. iron
b. nickel
c. cobalt
d. all of the above

d. all of the above

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The magnetic field is strongest when the:

a. magnetizing voltage is flowing
b. magnetizing current is flowing
c. material exhibits high coercive forces
d. magnetizing current is not flowing

b. magnetizing current is flowing

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The unit usually used to denote flux density is the:

a. gauss
b. henry
c. farad
d. ampere

a. gauss

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Why is it preferable to disassemble parts before magnetic particle inspection?

a. disassembly makes all surface areas visible
b. interfaces will create leakage fields which may confuse the inspection
c. it is usually easier to handle the disassembled parts
d. all of the above

d. all of the above

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False indications are caused by magnetic particles being held to the part by which of the following means?

a. gravity
b. mechanical
c. both a and b
d. none of the above

c. both a and b

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Which of the following will produce circular magnetism?

a. passing current through a coil.
b. placing the test part in a solenoid
c. passing current through the prods
d. yokes

c. passing current through the prods

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Which of the following is most often used for dry magnetic particle inspection?

a. full cycle direct current
b. half-wave rectified alternating current
c. high voltage, low amperage current.
d. direct current from electrolytic cells

b. half-wave rectified alternating current

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Comparing parts that have been circularly magnetized and those that have been longitudinally magnetized, which retains the most objectionable residual field if not demagnetized?

a. longitudinal
b. circular
c. vectored
d. remnant

a. longitudinal

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A rough forging that has received no further processing is magnetic particle tested. An indication is observed to run in every direction. It appears to extend deeply into the part and run perpendicular to the surface . It is very sharp. What is the probable identity of the indication?

a. forging burst
b. lap
c. flake
d. seam

a. forging burst

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Discontinuities in plate, or strip caused by pipe, inclusions, or blowholes in the original ingot which, after rolling, are usually flat and parallel to the outside surface are called:

a. seams
b. laminations
c. cracks
d. laps

b. laminations

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Half-wave rectified AC (HWDC) is used for detection of:

a. surface defects only
b. subsurface defects only
c. surface and subsurface defects
d. none of the above

c. surface and subsurface defects

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The pattern of iron powder sprinkled on a paper placed over a bar magnet is called a:

a. field survey
b. magnetometer
c. magnetograph
d. fluxmeter

c. magnetograph

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The lines of force that form a path around a crack in a ring magnet are called:

a. magnetic lines
b. leakage flux
c. field strength
d. longitudinal field

b. leakage flux

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An example of a non-relevant indication classified as a magnetic irregularity rather than an actual discontinuity could be caused by:

a. a slag pocket
b. grinding cracks
c. an abrupt change in the hardness of the part
d. none of the above

c. an abrupt change in the hardness of the part

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A magnetic discontinuity, which is a break in the magnetic uniformity of a part, is related to a sudden change in:

a. inductance
b. resistivity
c. capacitance
d. permeability

d. permeability

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What happens to a magnetic material which it reaches its Curie temp?

a. it becomes paramagnetic
b. it becomes diamagnetic
c. it becomes non-magnetic
d. it becomes radioactive

c. it becomes non-magnetic

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When a central conductor is magnetizing a cylinder, the field is most intense:

a. at the outer surface of the cylinder
b. halfway through the thickness of the cylinder wall
c. at the ends of the cylinder
d. at the inside surface of the cylinder

d. at the inside surface of the cylinder

When is the magnetic field strongest in an object being inspected by the magnetic particle method?

a. just prior to the current reversal when using AC current
b. just after the magnetizing current is shut off
c. while the magnetizing current is applied
d. when the magnetic particle powder is applied

c. while the magnetizing current

When withdrawing a part from the field around a coil and without changing the direction of current, which of the following has the least effect on demagnetizing the part?

a. alternating current
b. direct current
c. half-wave rectified alternating current
d. full-wave rectified current

b. direct current

Which of the following discontinuities occur as a result of the rolling process?

a. blowholes and pipes
b. laminations
c. fissures
d. all of the above

b. laminations

Which of the following discontinuities occur as a result of the forging process?

a. pipe
b. laps
c. laminations
d. all of the above

b. laps

The best shape for magnetic particles used in the dry powder method is:

a. flat
b. globular
c. long and slender
d. a mixture of B and C

d. a mixture of B and C

Which of the following is NOT a property of magnetic lines of force? a. They form closed loops which do not cross b. The density increases with increasing distance from the poles of a permanent magnet c. They are considered to have one direction d. They seek paths of least magnetic resistance or least reluctance

b. the density increases with increasing distance from the poles of a permanent magnet

Within conductors, electrons flow from: a. positive potential to negative potential b. positive potential to less positive potential c. negative potential to positive potential d. negative potential to greater negative potential

c. negative potential to positive potential

"Magnetic flux" is a term that relates to: a. describing the direction of current flow in an electromagnet b. the manner by which magnetism flows through space c. the number of lines of force associated with a magnetic field. d. permanent magnets only

c. the number of lines of force associated with a magnetic field

Flux density is defined as: a. 10^8 lines of flux (1 weber) b. the number of lines of force associated with a magnetic field c. the number of lines flux intercepting an area parallel with the flux d. the number of lines of flux intercepting an area perpendicular to the flux

d. the number of lines of flux intercepting an area perpendicular to the flux

The value of permeability is: a. a fixed value depending upon the type of material b. between 1 and 100 for all ferromagnetic materials c. a variable d. dependent upon the amount of magnetizing force necessary to overcome saturation

a. a fixed value dependent upon the type of material

Which of the following is NOT a limitation in the use of permanent magnets used to induce magnetism in ferromagnetic materials? a. It is difficult to magnetize large volumes with sufficient field strength b. adequate permanent magnets are too heavy to be readily handled by one person c. It is not practical to regulate the field strength d. Strong magnets may be difficult to remove from the material being magnetized

b. adequate permanent magnets are too heavy to readily handled by one person

Magnetism applied to a ferromagnetic part by a permanent magnet is called: a. direct magnetization b. direct current magnetization c. induced magnetization (indirect) d. reversed polarity magnetization

c. induced magnetization (indirect)

Direct current can be obtained from: a. batteries b. rectified alternating current c. generators d. all of the above

d. all of the above

The source which will supply the most power for magnetizing is: a. three phase AC, full wave rectified b. single phase AC, full wave rectified c. AC unrectified d. single phase AC, half-wave rectified

a. three phase AC, full-wave rectified

The flux density of the magnetism induced by a coil can be controlled by varying: a. the coil size b. the current in the coil c. the number of turns in the coil d. all of the above

d. all of the above

In which magnetizing method is the current passed directly through the part, thereby setting up a magnetic field at right angles to the current flow? a. longitudinal magnetization b. coil magnetization c. central conductor magnetization d. all of above e. none of the above

e. none of the above

The field in a section of ferromagnetic pipe being magnetized by means of a central conductor is the strongest at the: a. ends of the pipe b. outer surface of the pipe c. inside surface of the pipe d. middle of the pipe wall

c. inside surface of the pipe

An advantage of AC is that: a. it is most readily available b. equipment can be made lighter c. it leaves the part demagnetized d. all of the above

d. all of the above

A disadvantage of straight DC is that it: a. is more difficult to use with dry powder b. has poor penetrating power c. can only provide low flux densities d. cannot be used for residual magnetic particle testing

a. is more difficult to use with dry powder

HWDC is: a. pulsed DC b. used with dry powder c. used for inspecting welds d. all of the above

d. all of the above

Full-wave three-phase rectified AC: a. produces low-ripple DC b. uses a single bridge rectifier c. Is used in low current equipment d. is not practical as a source of magnetizing current

a. produces low-ripple DC

An indication is a defect under which of the following conditions? a. If it is greater than 1.5 inches long b. If it exceeds the limits of a code or standard c. If it is deep d. If it is in a fillet radius e. under all of the above conditions

b. if it exceeds the limits of a code or a standard

Paint will not affect the detection of a crack if: a. the paint is thick and the defect is subsurface b. the paint is thin and the crack is parallel to the direction of magnetization c. the crack is sharp and the paint is thin d. all of the above

c. the crack is sharp and the paint is thin

Which of the following would produce the best results for detection of a tight, shallow fatigue crack? a. dry red powder to give good consent b. wet suspension of gray powder to provide a low contrast c. wet suspension of black powder because it has a higher permeability d. all of the above would produce good results

c. wet suspension of black powder because it has a higher permeability

An advantage of magnetic rubber is that: a. it can be used on non-ferromagnetic materials b. it can be removed from the surface and examined using magnification c. it is very rapid test method d. the materials used are less expensive than dry powder

b. it can be removed from the surface and examined using magnification

The sensitivity of magnetic particle testing is greatest when the discontinuity is: a. parallel to the direction of the magnetic flux lines b. perpendicular to the flow of the magnetizing current c. perpendicular to the direction of the magnetic flux d. perpendicular to the line between prods.

c. perpendicular to the direction of the magnetic flux