McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
Chapters
| 1. |
Magnetic particles testing is most likely to find subsurface discontinuities in: |
| A. | Soft steels with high permeability |
| B. | Soft steels with low permeability |
| C. | Hardened steels with low permeability |
| D. | Hardened steels with high permeability |
| Answer» A. Soft steels with high permeability | |
| 2. |
Which of the following is not an advantage of magnetic particles testing? |
| A. | Fast and simple to perform |
| B. | Can detect discontinuities filled with foreign material |
| C. | Most reliable for finding surface cracks in all types of material |
| D. | Works well through a thin coat of paint |
| Answer» C. Most reliable for finding surface cracks in all types of material | |
| 3. |
Which of the following does not represent a limitation of magnetic particle testing? |
| A. | The type of materials which may be effectively tested |
| B. | The directionality of the magnetic field |
| C. | The need for demagnetization |
| D. | The ability to detect discontinuities filled with foreign material |
| Answer» D. The ability to detect discontinuities filled with foreign material | |
| 4. |
The most effective NDT method for locating surface cracks in ferromagnetic materials is: |
| A. | Ultrasonic testing |
| B. | Radiographic testing |
| C. | Magnetic particle testing |
| D. | Liquid penetrant testing |
| Answer» C. Magnetic particle testing | |
| 5. |
Which of the following may cause magnetic particle test indications? |
| A. | A joint between two ferromagnetic materials of different permeability |
| B. | A shrink fit joint in ferromagnetic materials |
| C. | A brazed joint in ferromagnetic materials |
| D. | All of the above |
| Answer» D. All of the above | |
| 6. |
A discontinuity which is produced during solidification of the molten metal is called: |
| A. | Inherent |
| B. | Processing |
| C. | Service |
| D. | None of the above |
| Answer» A. Inherent | |
| 7. |
Pipe would be classified as what type of discontinuity? |
| A. | Inherent |
| B. | Processing |
| C. | Service |
| D. | None of the above |
| Answer» A. Inherent | |
| 8. |
A seam would be classified as what type of discontinuity? |
| A. | Inherent |
| B. | Processing |
| C. | Service |
| D. | None of the above |
| Answer» B. Processing | |
| 9. |
A lamination in steel plate would be classified as what type of discontinuity? |
| A. | Inherent |
| B. | Processing |
| C. | Service |
| D. | None of the above |
| Answer» B. Processing | |
| 10. |
An internal rupture caused by working steel at improper temperatures is called a: |
| A. | Lap |
| B. | Cold shut |
| C. | Forging burst |
| D. | Slag inclusion |
| Answer» C. Forging burst | |
| 11. |
Cracks which are caused by alternating stresses above a critical level are called: |
| A. | Stress corrosion cracks |
| B. | Cycling cracks |
| C. | Critical cracks |
| D. | Fatigue cracks |
| Answer» D. Fatigue cracks | |
| 12. |
Cracks which are caused by a combination of tensile stress and corrosion are called: |
| A. | Stress corrosion cracks |
| B. | Cycling cracks |
| C. | Critical cracks |
| D. | Fatigue cracks |
| Answer» A. Stress corrosion cracks | |
| 13. |
Which of the following are ferromagnetic materials? |
| A. | Aluminium, iron, copper |
| B. | Iron, copper, nickel |
| C. | Copper, aluminium, silver |
| D. | Iron, cobalt, nickel |
| Answer» D. Iron, cobalt, nickel | |
| 14. |
The reverse magnetising force necessary to remove a residual magnetic field from a test piece after it has been magnetically saturated is called: |
| A. | Hysteresis |
| B. | Coercive force |
| C. | Demagnetising flux |
| D. | Reverse saturation |
| Answer» B. Coercive force | |
| 15. |
Magnetic lines of force enter and leave a magnet at: |
| A. | Saturation |
| B. | L/D ratios of greater than 4 to 1 |
| C. | Flux concentration points |
| D. | Poles |
| Answer» D. Poles | |
| 16. |
The ease with which a magnetic field can be established in a test piece is called: |
| A. | Reluctance |
| B. | Retentivity |
| C. | Permeability |
| D. | Electromagnetism |
| Answer» C. Permeability | |
| 17. |
Opposition to establishment of a magnetic field is called: |
| A. | Reluctance |
| B. | Retentivity |
| C. | Permeability |
| D. | Electromagnetism |
| Answer» A. Reluctance | |
| 18. |
The ability of a material to remain magnetic after the magnetising force is removed is called: |
| A. | Reluctance |
| B. | Retentivity |
| C. | Permeability |
| D. | Electromagnetism |
| Answer» B. Retentivity | |
| 19. |
A magnetic field which is contained completely within the test piece is called a: |
| A. | Confined field |
| B. | Longitudinal field |
| C. | Circular field |
| D. | Saturated field |
| Answer» C. Circular field | |
| 20. |
Which of the following produces a circular field? |
| A. | Coil |
| B. | Head shot |
| C. | Yoke |
| D. | All of the above |
| Answer» B. Head shot | |
| 21. |
A technique used to find transverse discontinuities at the ends of longitudinally magnetised bars by the use of transient currents is called: |
| A. | A coil technique |
| B. | A fast break technique |
| C. | A yoke technique |
| D. | A head shot |
| Answer» B. A fast break technique | |
| 22. |
A leakage field is strongest when a discontinuity interrupts the magnetic flux lines at an angle of: |
| A. | Zero degrees |
| B. | 45 degrees |
| C. | 90 degrees |
| D. | 180 degrees |
| Answer» C. 90 degrees | |
| 23. |
The best method of inducing a circular field in a tube is by a: |
| A. | Central conductor |
| B. | Head shot |
| C. | Coil |
| D. | Prod technique |
| Answer» A. Central conductor | |
| 24. |
Magnetic flux density is zero at: |
| A. | The inside surface of a tube magnetised with a central conductor |
| B. | The outside surface of a tube magnetised with a central conductor |
| C. | The outside surface of a bar magnetised with a head shot |
| D. | The centre of a bar magnetised with a head shot |
| Answer» D. The centre of a bar magnetised with a head shot | |
| 25. |
Magnetic flux density is highest at: |
| A. | The outside surface of a non-ferromagnetic tube magnetised with a central conductor |
| B. | The inside surface of a non-ferromagnetic tube magnetised with a central conductor |
| C. | The outside surface of a ferromagnetic tube magnetised with a central conductor |
| D. | The inside surface of a ferromagnetic tube magnetised with a central conductor |
| Answer» D. The inside surface of a ferromagnetic tube magnetised with a central conductor | |
| 26. |
An important consideration when using a direct contact method is: |
| A. | Lifting power of the yoke |
| B. | Coil diameter |
| C. | Preventing arc burns |
| D. | Field strength adjacent to the coil inside diameter |
| Answer» C. Preventing arc burns | |
| 27. |
A prod method would be most sensitive to cracks: |
| A. | Parallel to a line connecting the prod contact points |
| B. | Tangential to a radius from each prod contact point |
| C. | Perpendicular to a line connecting the prod contact points |
| D. | Perpendicular to the long axis of the coil |
| Answer» A. Parallel to a line connecting the prod contact points | |
| 28. |
When using prods, arc burns may be caused by which of the following? |
| A. | Dirty contact tips |
| B. | Inadequate pressure |
| C. | Too large a magnetic current |
| D. | All of the above |
| Answer» D. All of the above | |
| 29. |
The important difference between AC and DC current for magnetic particle testing purposes is: |
| A. | The skin effect caused by DC adds mobility to the magnetic particles |
| B. | The resulting AC magnetic fields are more difficult to demagnetize |
| C. | The DC magnetic fields are more penetrating |
| D. | The AC magnetic fields are stronger |
| Answer» C. The DC magnetic fields are more penetrating | |
| 30. |
The ‘skin’ effect would be most noticeable in which of the following? |
| A. | A magnetic conductor carrying a DC current |
| B. | A nonmagnetic conductor carrying a DC current |
| C. | A magnetic conductor carrying a 50 Hz AC current |
| D. | A nonmagnetic conductor carrying a 50 Hz AC current |
| Answer» D. A nonmagnetic conductor carrying a 50 Hz AC current | |
| 31. |
The most common source of DC current for magnetic particle testing is: |
| A. | Motor generators |
| B. | Rectified AC |
| C. | Storage batteries |
| D. | None of the above |
| Answer» B. Rectified AC | |
| 32. |
Fields generated in ferromagnetic material with AC current are useful for locating: |
| A. | All discontinuities |
| B. | Surface cracks |
| C. | Subsurface discontinuities |
| D. | Internal porosity |
| Answer» B. Surface cracks | |
| 33. |
A common rule of thumb to use for current required in circular magnetisation: |
| A. | 1000 amps/25mm of diameter |
| B. | 1000 ampere turns/25mm of diameter |
| C. | 1000 amps/25mm of prod spacing |
| D. | None of the above |
| Answer» B. 1000 ampere turns/25mm of diameter | |
| 34. |
The formula, NI = 45000/(L/D), is used to calculate the proper magnetising current for: |
| A. | Prod magnetization |
| B. | A head shot |
| C. | A central conductor |
| D. | Coil magnetisation |
| Answer» D. Coil magnetisation | |
| 35. |
The formula, NI = 45000/(L/D), gives proper magnetising current for a coil, regardless of coil size as long as: |
| A. | The test piece is not larger than 1/10 the cross sectional area of the coil |
| B. | AC current only is used |
| C. | The test piece essentially fills the coil |
| D. | The test piece is held tightly against the coil |
| Answer» A. The test piece is not larger than 1/10 the cross sectional area of the coil | |
| 36. |
For direct contact magnetising methods, the magnetic field is oriented in what direction relative to the current direction? |
| A. | Parallel |
| B. | At 45 degrees |
| C. | At 90 degrees |
| D. | At 180 degrees |
| Answer» C. At 90 degrees | |
| 37. |
For direct contact magnetising methods, current should be flowing in what direction relative to expected discontinuities? |
| A. | Parallel |
| B. | At 45 degrees |
| C. | At 90 degrees |
| D. | At 180 degrees |
| Answer» A. Parallel | |
| 38. |
What is the magnetic field strength at the surface of a 100 mm diameter bar as compared to that at the surface of a 50 mm diameter bar, each carrying 1000 amps of current? |
| A. | Twice |
| B. | One half |
| C. | One quarter |
| D. | Four times |
| Answer» B. One half | |
| 39. |
What is the magnetic field strength at the surface of a 25mm diameter bar as compared to that at the surface of a 50mm diameter bar, each carrying 1000 amps of current? |
| A. | Twice |
| B. | One half |
| C. | One quarter |
| D. | Four times |
| Answer» A. Twice | |
| 40. |
The magnetic field outside a conductor decreases: |
| A. | Exponentially |
| B. | In a linear manner |
| C. | Inversely with distance |
| D. | Inversely with the square of distance |
| Answer» B. In a linear manner | |
| 41. |
How is the magnetic field strength at the surface of a magnetic conductor having permeability, µ, related to the magnetic field strength, F, at the surface of a nonmagnetic conductor carrying the same current? |
| A. | F × µ |
| B. | Same |
| C. | F/µ |
| D. | Not related |
| Answer» B. Same | |
| 42. |
Compared to the magnetic field strength at the outer surface, the magnetic field strength, at the centre of a hollow, nonmagnetic conductor carrying DC current is: |
| A. | I/D |
| B. | The same |
| C. | Zero |
| D. | Need more information to determine |
| Answer» C. Zero | |
| 43. |
How is the magnetic field strength, F, just outside a magnetic conductor having permeability, µ, related to that just outside a nonmagnetic conductor of the same size, carrying the same current? |
| A. | F × µ |
| B. | Same |
| C. | (F)/µ |
| D. | Not related |
| Answer» B. Same | |
| 44. |
Which of the following describes the shape of particles used for dry magnetic particle testing? |
| A. | Spherical |
| B. | Angular |
| C. | Elongated |
| D. | Mixture of elongated and globular |
| Answer» D. Mixture of elongated and globular | |
| 45. |
Which of the following particles would be most sensitive? |
| A. | Wet |
| B. | Dry |
| C. | Depends on the test piece permeability |
| D. | None of the above |
| Answer» B. Dry | |
| 46. |
Which of the following colours is readily available for magnetic particle test powder? |
| A. | Red |
| B. | Gray |
| C. | Black |
| D. | All of the above |
| Answer» D. All of the above | |
| 47. |
A magnetic particle testing technique in which the test piece is magnetised and magnetic particles applied after the magnetising force has been removed is called the: |
| A. | Magnetic method |
| B. | Continuous method |
| C. | Residual method |
| D. | Discontinuous method |
| Answer» C. Residual method | |
| 48. |
Which of the following characteristics would be most important in a test piece which is to be tested using the residual method? |
| A. | High rententivity |
| B. | High permeability |
| C. | Low reluctance |
| D. | Low permeability |
| Answer» A. High rententivity | |
| 49. |
The wet method is superior to dry particles for detecting: |
| A. | Subsurface discontinuities |
| B. | Fine surface cracks |
| C. | Open surface cracks |
| D. | None of the above |
| Answer» B. Fine surface cracks | |
| 50. |
Selection of magnetic particle colour is based on: |
| A. | Optimum performance of magnetic particle/developer |
| B. | Colour of inspection light available |
| C. | Obtaining maximum contrast with the test piece background |
| D. | Optimum colour response of the human eye |
| Answer» C. Obtaining maximum contrast with the test piece background | |
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