MPI 2 Questions Flashcards
Which of the following types of magnetic field exhibits no external flux leakage in the absence of discontinuities?
-Vectored
-Longitudinal
-Circular
-All of the above exhibit external flux leakage
Circular
What is the value given in SI unites for the permeability of free space?
- 1
- 0.72 Tesla
- 5 Gausss
- 4 x 10-7 Henries/M
4 x 10-7 Henries/M
When a ferromagnetic material becomes magentised under the influence of an increasing stronger magnetising force, which of the following occurs?
-Domains become larger and fewer in number
-Domains become smaller and fewer in number -Domains become smaller and greater in
-Domains become larger and greater in number
Domains become larger and fewer in number
Which of the following would constitute a low reluctance preferential path?
-Non metallic inclusion
-Ferromagnetic particle
-Copper
-Air
Ferromagnetic particle
When carrying out magnetic particle inspection, flux density is generated into the ferromagnetic material being inspected. One unit of flux density is the gauss. How many webers per square metre equal one gauss?
-0.72
-10^4
-2 x 1 0 - 6
-0.00072
10^4
The right hand rule shows which of the following relationships?
-Electron flow from negative to positive with a magnetic field parallel to the current flow
-Current flow from negative to positive with a magnetic field perpendicular to the current flow
-Electron flow from positive to negative with a magnetic field parrallel to the current
-Current flow from positive to negative with a magnetic field peroendicular to the
current flow
Current flow from positive to negative with a magnetic field peroendicular to the current flow
A ferromagnetic material with a steep initial curve will have which of the following properties?
-Low permeability
-Low coercivity
-High reluctance
-The material will have all of the above properties
Low coercivity
When magnetising with alternating current, a lagging effect occurs where by the magnetic flux density within the metrial lags behind the applied magentising force. What is this phenomena called?
-Retentivity
-Reluctance
-Hysteresis
-Permeability
Hysteresis
Direct induction will always generate which of the following types of magnetic field?
-Circular
-Longitudinal
-Vectored
-All the above could be generated
Circular
The curie point is the temperature at which a ferromagnetic material will become paramagnetic and as such loose its high susceptibility to magnetisation. What is the curie point temperature for cobalt?
-770 Degrees Farenheit
-1130 Degrees Farenheit
-770 Degrees Celsius
-1130 Degrees Celsius
1130 Degrees Celsius
The magnetic flux lines which flow through a bar magnet form closed loops but can be broken by which of the following?
- A change in permeability
- A non metallic inclusion
- A crack
- None of the above will cause a break in a flux line
None of the above will cause a break in a flux line
The earth itself has a magnetic effect which can affect ferromagnetic materials. Which of the following best describes this magnetic effect?
-Mono-Polar
-Bi-Polar
-Multi-Polar
-Circular Magnetic Fields
Bi-Polar
A fault in magnetised material will best be detected when it lies in which of the following directions?
-Parallel to the magnetic field
-Perpendicular to the magnetic field
-Parrallel to the magnetising current
-Perpendicular to the magnetising force
-Both parallel to the magnetic field and perpendicular to the the magnetising force
-Both perpendicular to the magnetic field and parrallel to the magnetising current
Both perpendicular to the magnetic field and parrallel to the magnetising current
A change in which property of between the material being inspected and the discontinuity to be detected generates flux leakage?
-Conductivity
-Permeability
-Oxidisation
-Hysteresis
Permeability
Which of the following materials would be considered to be have a permeability much greater than that of air?
-Aluminium
-Bismuth
-Zinc
-Gadolinium
-None of the above have a permeability much greater than air
Gadolinium
Which of the following flux leakage curvatures will have the greatest attraction for magnetic particles?
-Low Curvature
-No Curvature
-Highly curved
-Curvature has no effect on magnetic particle attraction
Highly curved
A discontinuity which generates flux leakage on the surface of a ferromagnetic material will have a high factor for which of the following properties?
-Permeability
-Reluctance
-Retentivity
-Both reluctance and retentivity
Reluctance
Which of the following decribes a Hall Effect Element Sensor?
-Two coils placed mutually perpendicular
-A P-N junction within a semi-conductor
-Current carrying semi-conductor crystals
-Coils wound around cylindrical ferrite
Current carrying semi-conductor crystals
Which of the following materials will have the largest relative permeability value?
-0.9% Carbon
- Nickel (99% annealed)
-Cobalt (99% annealed)
-Aluminium
Nickel (99% annealed)
Which of the following is an advantage of three phase electricity over single phase electricity?
-More particle mobility especially when using dry powder
-Better detection of surface breaking faults due to skin effect
-Less current input per phase
-All of the above are advantages
Less current input per phase
When using field flow magnetisation (solenoid heads) a reference standard whould be used with a known artificial discontinuity located where on the standard?
-At the centre of the cross section
-At a position one third along itself
-In the centre of the materials length
-None of the above should be used to evaluate field flow magnetisation
In the centre of the materials length
For what reasons are laminated iron cores used for the production of AC electromagnetic yokes?
-They are easier to encapsulate in plastic
-Better efficiency in the generation of magnetic fields
-Solid iron would be too heavy
-Solid iron would not give the skin effect
Better efficiency in the generation of magnetic fields
When using a threading bar (central conductor) to test a hollow tube, it needs to be placed where in relation to the tubes inner diameter for optimum inspection to be carried out?
-In the centre of the tube
-Adjacent to the inner circumference of the tube
-Adjacent to the outer circumference of the tube
-The conductor can be placed in any of the above positions
Adjacent to the inner circumference of the tube
The output of power packs needed to magnetize forgings and castings too large to place in stationary units is in the range?
- 6 - 2 0 M A
- 0.25 - 3 KA
- 6 - 2 0 K A
- 0.25 - 3 MA
6 - 20 KA
When direct current is passed through a central conductor inserted through a hollow tubes at what point is the magnetic field intensity essentially zero?
-At the inner circumference of the tube
-At the exact centre of the threading bar
-On the surface of teh tube
-Both at the inner circumference of the tube and at the exact centre of the threading bar
At the exact centre of the threading bar
Under optimum conditions with dry powder for substances flaw detection, which of the following waveforms would best be used?
-Direct current
-Three phase rectified alternating current - full wave
-Alternating current
-Single phase rectified alternating current - half wave
Single phase rectified alternating current - half wave
Under optimum conditions magnetic particles used with the wet method are made from iron oxide rather than higer permeability iron. What are the reasons for this choice?
-Iron oxide is more dense than iron
-Iron oxide is less dense than iron
-Iron oxide falls out of suspension quicker than iron
-Iron falls out of suspension quicker than iron oxide
-Both Iron oxide is less dense than iron and Iron falls out of suspension quicker than iron oxide
Both Iron oxide is less dense than iron and Iron falls out of suspension quicker than iron oxide
The following is a standard definition, ‘A small portable device containing artificial discontinuities used to determine when the correct magnetising conditions have been achieved.’ Which of the following is correct?
-Flux meter
-Flux indicator
-Gauss meter
-Image quality indicator
Flux indicator
Which of the following techniques would best be used to detect circumferential faults in rings without damaging the parts surface in one shot?
-Direct induction between contract heads across diameter of ring
-A threading bar
-Induced current generating a toroidal magnetic field
-Magnetic flow across the diamter of ring
Induced current generating a toroidal magnetic field
Using 10 amps per mm diameter how much current is to be used to magnetise a bar 25 x 20 mm x 2 metres long on a bench unit using current flow?
-286 amps
-320 amps
-160 amps
-143 amps
286 amps
Magnetic particles form indications around flux leakages due to which of the following?
-Magnetism follows the path of most resistance -Iron particles are good conductors of electricity -Air has a higher reluctance than iron or iron oxide
-All of the above are true
Air has a higher reluctance than iron or iron oxide
Which of the following materials could be inspected using the residual technique due to the materials high retentivity?
-Low carbon steel
-Heat treated high carbon steel
-Austenitic stainless steel
-Ferritic stainless steel
Heat treated high carbon steel
With prods using half wave direct current, the magnetic field within the material is dependent on which of the following factors?
-Amount of current used
-The permeability of the inspected material
-The distance between prod tips when positioned on the chromed hard facing
-Both the amount of current used and the permeability of the inspected material
-All of the above
Both the amount of current used and the permeability of the inspected material
Which of the following techniques is most likely to be used when a permanent record of the inside of a threaded bolt hole is required?
-Strippable lacquer
-Photography
-Magnetic Rubber
-Any of the above may be used
Magnetic Rubber
If two magnetic fields of equal intensity are induced into a ferromagnetic material at 90 degrees to each other in the longitudinal and transverse directions, which of the following faults could be detected?
-Faults only at 45 degrees
-Longitudinal faults only
-Transverse faults only
-Faults lying in a position 45 degrees in either direction from a direction at 45 degrees from the longitudinal direction
Faults lying in a position 45 degrees in either direction from a direction at 45 degrees from the longitudinal direction
Why would a photometer be used when carrying out fluorescent magnetic particle inspection?
-To measure the black light given off from a UV-A lamp
-To measure radiation between 320 nM - 400 nM
-To measure radiation between 400 nM - 700 nM
-None of the above
To measure radiation between 400 nM - 700 nM
Photopic vision refers to vision used when carrying out which type of inspection?
-Non fluorescent inspection
-Fluorescent inspection
-Dry powder inspection
-All of the above
-Both Fluorescent inspection and dry powder inspection
Non fluorescent inspection
If the levels of electric current used to magnetize ferromagnetic material are greatly exceeded, what phenomena can occur when magnetic particles are applied?
-The particles are forced off the parts surface due to vibrational impingement
-The particles are forced together around faults showing an indication much larger than
the fault below
-The particles are held over the entire surface giving an overall background which may be confusing
-The part will very quickly melt
The particles are held over the entire surface giving an overall background which may be confusing
Which of the following would be used to render water a suitable carrier fluid for use in the wet
magnetic particle technique?
-De-wetting agent
-Rust inhibitor
-Foaming agent
-All of the above could be used
Rust inhibitor
Why do prod tips need to be kept clean and free from contaminants?
-The contamination reduces the resistance so increasing current flow
-Clean prod tips have less chance of arcing
-Clean prods conduct current through scale much better
-The increase in resistance with dirty prods reduces the current output
-Both clean prod tips have less chance of arcing and the increase in resistance with dirty prods reduces the current output
Both clean prod tips have less chance of arcing and the increase in resistance with dirty prods reduces the current output
For one person to use prods unaided which of the following would be the most suitable approach?
-Hold both prods in one hand with the detaching medium in the other
-Use the residual technique as the detecting medium can be applied after the magnetizing force
-Use a magnetic leech attachment to one prod with the other in one hand and the detecting medium in the other
-Prods should not be used by one person due to safety precautions
Use a magnetic leech attachment to one prod with the other in one hand and the detecting medium in the other
Subjecting a ferromagnetic material to a magnetising force which reserves in a polarity whilst at the
same time remains the same strength, has what effect?
-Demagnetization
-Magnetization
-None of the above
-Either demagnetisation or magnetization
Magnetization
For the highest possible sensitivity when using the continuous method which of the following application techniques should be used?
-Apply current whilst applying wet magnetic ink by spray
-Apply current whilst part is immersed in wet ink followed by removal whilst current still
flows
-Apply current whilst part is immersed in wet ink. Stop flow of current whilst removing
-All the above give the same sensitivity
Apply current whilst part is immersed in wet ink followed by removal whilst current still flows
Which of the following processes could have the effect of reducing the gradient of the B/H curve for a particular ferromagnetic material?
-Cold rolling
-Subjecting the material to stress
-Annealing
-Work hardening
Annealing
An arrangement consisting of 2 C-shaped yokes connected together at right angles will give rise to which of the following when testing a weldment?
-A circular magnetic field
-A longitudinal magnetic field to detect longitudinal faults
-A vectored field to detect longitudinal faults only
-A vectored field which will detect both transverse and longitudinal faults
A vectored field which will detect both transverse and longitudinal faults
Which type of surface condition would be most conducive to inspection using multi direction magnetisation by switching from one field to another at 90 degrees to the first?
-Rough as cast
-Brightly machined
-Electro polished
-Surface finish has no influence on particle build up using multi -directional magnetisation
Rough as cast
Why is demagnetization carried out prior to magnetic particle inspection in areas such as the aerospace industry?
-There is the possibility of a pre-existing field which will cause an actual magnetic field within the tested material in an unfavourable direction
-The pre-existing field may nullify the applied field
-Demagnetization is not carried out prior to inspection
-There is the possibility of a pre-existing field which will cause an actual magnetic field within the tested material in an unfavourable direction and the pre-existing field may nullify the applied field
There is the possibility of a pre-existing field which will cause an actual magnetic field within the tested material in an unfavourable direction and the pre-existing field may nullify the applied field
When using a central conductor to magnetize a ferromagnetic tube magnetic field strength is greatest at what point within the system?
-Outside surface of threading bar
-Outside surface of tube
-Inside surface of tube
-At none of the above positions
Inside surface of tube
What is the difficulty when inspecting complex parts with differing cross-sections?
-Under magnetization of large sections
-Over magnetization of small sections masking certain areas
-Demagnetization prior to inspection
-Both under magnetisation of large sections and over magnetisation of small sections masking certain areas could be correct
Both under magnetisation of large sections and over magnetisation of small sections masking certain areas could be correct
When photographing magnetic particle indications, highest definiton is obtained when which of the following films are used?
-Slow film - coarse grain
-Slow film - fine grain
-Fast film - coarse grain
-Fast film - fine grain
Slow film - fine grain
Which of the following carrier fluids used with wet magnetic inks will have the smallest change in viscosity between the temperatures of 0 degrees celsius and 50 degrees celsius?
-Water
-Oil
-Kerosene
-All will react in the same way to changes in temperature
Water
Permanent magnets can be made out of which of the following materials?
-Aluminium, Cobalt, and Nickel
-Molybdenum and Aluminium
-Copper, Nickel and Iron
-Copper and Aluminium
-Both Aluminium, Cobalt and Nickel, and Copper, Nickel and Iron
-Both Molybdenum and Aluminium, and Copper and Aluminium
Both Aluminium, Cobalt and Nickel, and Copper, Nickel and Iron
When attempting to demagnetize with an electromagnetic yoke, which of the following will be most effective?
-Use a DC yoke and withdraw whilst switched off
-Use an AC yoke and withdraw whilst energized
-Use a DC yoke and withdraw whilst energized
-Use an AC yoke and withdraw whilst switched off
-Use a single pole AC electromagnet and withdraw whilst energised
Use an AC yoke and withdraw whilst energised