Wednesday, 1 June 2011

Asnt MT Level 1 - set 1

Magnetic Particle Testing Method (40 Questions)

1. "Magnetic particle" is a nondestructive examination method used for:
a. locating surface discontinuities
b. locating near surface discontinuities
c. both a and b
d. detecting material separation

2. 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

3. The permeability 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

4. 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

5. Why are magnetic particles available in different colors?
a. for color contrast with the part surface
b. to enhance the detection of indications
c. both a and b
d. different colors are used with different magnetic flux values

6. Which of the following can be magnetized?
a. iron
b. nickel
c. cobalt
d. all of the above

7. 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

8. If a crack exists in a circular magnet, the attraction of magnetic particles to the crack is caused by a:
a. coercive force
b. leakage field
c. Doppler effect
d. high reluctance at the crack
9. The unit usually used to denote flux density is the:
a. gauss
b. henry
c. farad
d. ampere

10. Which statement is true when related to magnetic lines of force?
a. they never cross
b. they are most dense at the poles of a magnet
c. they seek the path of least resistance
d. all of the above

11. Magnetic flux lines which are parallel to a discontinuity produce:
a. strong indications
b. weak indications
c. no indications
d. fuzzy indications

12. A part is adaptable to magnetic particle inspection if:
a. it is attached to an electrostatic field
b. the material is ferromagnetic
c. the material is nonferrous
d. the material is an electric conductor

13. What rule describes the direction of current flow (+ to -) when lines of magnetic force surround a conductor?
a. the left hand rule
b. the right hand rule
c. the flux rule
d. the reluctance rule

14. The magnitude of the residual magnetic field in specimen is dependent on the:
a. L/D ratio (length to diameter)
b. strength of the applied magnetizing force
c. right hand rule
d. left hand rule

15. The proper number of ampere-turns for a given test specimen is determined by:
a. its length
b. the material
c. both a and b
d. its diameter

16. A circular field may be induced into a specimen by:
a. direct induction (head shot)
b. direct induction (prods)
c. central condustor
d. all of the above

17. An electrical yoke produces:
a. a longitudinal field
b. a circular field
c. alternating fields
d. a swinging field

18. A coil around the part produces:
a. a circular field
b. a longitudinal field
c. either a or b depending on the type of current applied
d. an intermittent field

19. In longitudinal magnetization, the proper term for calculating magnetizing force is:
a. amperes
b. ampere-turns
c. watts
d. ohms

20. Magnetic lines of force:
a. travel in straight lines
b. form a closed loop
c. are randomly oriented
d overlay in highly ferromagnetic materials

21. A magnetic particle build-up from a discontinuity is strongest when the discontinuity is oriented:
a. 180° to the magnetic field
b. 45° to the magnetic field
c. 90° to the magnetic field
d  90° to the current flow

22.  A specimen may be demagnetized by:
a.  heat treatment above Curie temperature
b. an AC coil
c.  reversing DC fields
d. all of the above

23. Which of the following is an advantage of magnetic particle testing over penetrant testing?
a. it can detect surface discontinuities with foreign material imbedded in them
b. it is faster on individual parts
c. it can detect near-surface discontinuities
d. all of the above

24. The amount of amperage used for magnetic particle inspection using the prod method is determined from the:
a. type of material
b. distance between the prod
c. diameter of the part
d. total length of the part

25. The flux within and surrounding a magnetized part or around a conductor carrying a current is known as:
a. saturation point
b. magnetic field
c. ferromagnetic
d. paramagnetic

26. The areas on a magnetized part from which the magnetic field is leaving or returning into the part are called:
a. salient points
b. defects
c. magnetic poles
d. nodes

27. A metal that is difficult to magnetize is said to have:
a. high permeability
b. low permeability
c. high reluctance
d. low retentivity

28. The magnetism that remains in a piece of magnetizable material after the magnetizing force has been removed is called the:
a. tramp field
b. residual field
c. damped field
d. permanent field

29. 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

30. Subsurface discontinuity indications usually appear:
a. sharp and distinct
b. sharp and wide
c. wide and fuzzy
d. high and loosely held

31. Which residual field is most difficult to demagnetize?
a. longitudinal
b. circular
c. vector
d. binodal

32. Which technique is the most sensitive?
a. continuous
b. residual
c. interrupted
d. counter-current

33. Which type of current brings out surface indications most clearly?
a. AC
b. DC
c. pulsed DC
d. DC with surge

34. Fluorescent magnetic particle indications should be inspected under:
a. fluorescent light
b. any light
c. black light
d. neon light

35. Inspecting a part by magnetizing, removing the current flow, and then applying the medium is called the:
a. continuous method
b. wet method
c. residual method
d. dry method

36. 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

37. Which of the following is the most effective method for the detection of extremely deep lying defects?
a. dry residual method using DC with surge
b. wet continuous method using half-wave rectified current
c. wet residual method
d. dry continuous method using half-wave rectified current with prods

38. A curve is sometimes drawn to show graphically the relation of the magnetizing force to the strength of the magnetic field produced in a certain material. This curve is known as the:
a. magnetic force curve
b. hysteresis curve
c. saturation curve
d. induction curve

39. What method provides greater sensitivity, particularly in locating subsurface discontinuities?
a. continuous
b. residual
c. circular
d. longitudinal

40. When there is absolutely no pattern or distribution of magnetic particles, the possible cause is that:
a. the material is nonmagnetic
b. the amperage setting is too low
c. no current is being applied
d. any of the above could be true



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