McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
Chapters
| 351. |
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 |
| Answer» B. Half wave rectified alternating current | |
| 352. |
When a magnetic field is induced in a part with prods spaced 150mm apart, the field is: |
| A. | Solenoidal |
| B. | Circular |
| C. | Longitudinal |
| D. | Distorted trapezoidal |
| Answer» B. Circular | |
| 353. |
With current flowing from + to - in a coil, a longitudinal field is created. Which of the following may be used to establish the direction of the magnetic field? |
| A. | Left hand rule |
| B. | Right hand rule |
| C. | Ohms law |
| D. | There is no relevant law |
| Answer» B. Right hand rule | |
| 354. |
Which form of magnetisation is easiest to control in most parts? |
| A. | Longitudinal magnetisation |
| B. | Permanent magnetism |
| C. | Circular magnetization |
| D. | Parallel magnetization |
| Answer» A. Longitudinal magnetisation | |
| 355. |
The strength of a magnetic field within a coil is determined by: |
| A. | The current in the coil |
| B. | The number of turns in the coil\ |
| C. | The diameter of the coil |
| D. | All of the above factors |
| Answer» D. All of the above factors | |
| 356. |
The field in a section of pipe being magnetised by means of a central conductor is stronger at: |
| A. | The ends of the pipe |
| B. | The outer surface of the pipe |
| C. | The inside surface of the pipe |
| D. | The middle of the pipe wall |
| Answer» C. The inside surface of the pipe | |
| 357. |
The space within and surrounding a magnetized part of a conductor carrying a current is known as: |
| A. | Saturation point |
| B. | Magnetic field |
| C. | Ferromagnetic |
| D. | Paramagnetic |
| Answer» B. Magnetic field | |
| 358. |
Subjecting the part to a magnetic field that is constantly reversing in polarity and gradually diminishing in strength accomplishes which of the following: |
| A. | Magnetises the part |
| B. | Removes residual field from the part |
| C. | Soaks in the flux density |
| D. | Helps find deep lying defects |
| Answer» B. Removes residual field from the part | |
| 359. |
The type of method most frequently used with mobile equipment is the: |
| A. | Indirect induction method |
| B. | Wet method with auxiliary tank |
| C. | Yoke method |
| D. | Dry magnetic particle powder method |
| Answer» D. Dry magnetic particle powder method | |
| 360. |
Which of the following is NOT a liquid vehicle in which particles are suspended in magnetic particle testing: |
| A. | Water treated with a wetting agent |
| B. | Kerosene |
| C. | Gasoline |
| D. | Water treated with antifoam |
| Answer» C. Gasoline | |
| 361. |
The most common cause of non relevant indications in MT is: |
| A. | Over magnetisation |
| B. | Low amperage |
| C. | High flux density |
| D. | Under magnetisation |
| Answer» A. Over magnetisation | |
| 362. |
When a ferromagnetic material is in an unmagnetized state, the domains are: |
| A. | Aligned in a North and South direction |
| B. | Aligned in an East West direction |
| C. | Randomly organized |
| D. | Balanced to produce a gauss rating of 2 |
| Answer» C. Randomly organized | |
| 363. |
Paramagnetic materials: |
| A. | Are commonly inspected using magnetic particle testing |
| B. | Are affected by magnetic fields |
| C. | Cannot be magnetized |
| D. | Have low reluctance to establishment of magnetic flux |
| Answer» B. Are affected by magnetic fields | |
| 364. |
What type of magnetization uses the formula: I = 45000/(L/D)N where I is the current in Amperes, N the number of turns of the magnetizing coil, L the length of the cylindrical test piece and D its diameter. |
| A. | Circular |
| B. | Longitudinal |
| C. | Swinging field |
| D. | Central conductor |
| Answer» B. Longitudinal | |
| 365. |
The magnetic field is the strongest when: |
| A. | The magnetising current is flowing |
| B. | The magnetising voltage is applied |
| C. | The leakage field is flowing |
| D. | The magnetising current is off |
| Answer» A. The magnetising current is flowing | |
| 366. |
The retentivity of a material describes: |
| A. | The length of time required to demagnetise it |
| B. | The depth of the magnetic field in the part |
| C. | The ability to retain the magnetic field |
| D. | The ease with which it can be demagnetized |
| Answer» C. The ability to retain the magnetic field | |
| 367. |
A material with a wider hysteresis loop has: |
| A. | Lower reluctance |
| B. | Lower residual magnetism |
| C. | Higher residual magnetism |
| D. | Higher permeability |
| Answer» C. Higher residual magnetism | |
| 368. |
The unit usually used to denote flux density is the: |
| A. | Henry |
| B. | Angstrom |
| C. | Gauss |
| D. | Ampere |
| Answer» C. Gauss | |
| 369. |
Which technique is the most sensitive? |
| A. | Residual |
| B. | Continuous |
| C. | Permanent |
| D. | Interrupted |
| Answer» B. Continuous | |
| 370. |
What rule describes the direction of current flow (+ to -) when lines of magnetic force surround a conductor? |
| A. | Left hand rule |
| B. | Right hand rule |
| C. | Flux density rule |
| D. | Reluctance rule |
| Answer» B. Right hand rule | |
| 371. |
The opposition that a ferromagnetic material shows to the establishment of a magnetic field is called: |
| A. | Retentivity |
| B. | Reluctance |
| C. | Coercive force |
| D. | Permeability |
| Answer» B. Reluctance | |
| 372. |
The magnetism which remains in a piece of magnetisable material after the magnetising force has been removed is called the: |
| A. | Tramp field |
| B. | Residual field |
| C. | Damped field |
| D. | Permanent field |
| Answer» B. Residual field | |
| 373. |
A material with a narrower hysteresis loop has: |
| A. | Higher permeability |
| B. | Lower retentivity |
| C. | Lower coercive force |
| D. | All of the above |
| Answer» D. All of the above | |
| 374. |
The correct number of ampere-turns for a given test specimen is determined by: |
| A. | Its length |
| B. | The material and its diameter |
| C. | Both the length and the material |
| D. | Its diameter and length |
| Answer» D. Its diameter and length | |
| 375. |
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 distance from the poles of a permanent magnet |
| C. | Hey are considered to have direction |
| D. | They seek paths of least magnetic resistance or least reluctance |
| Answer» B. The density increases with distance from the poles of a permanent magnet | |
| 376. |
Surrounding an electromagnet, the magnetic field is strongest: |
| A. | Immediately after the current ceases to flow |
| B. | While the magnetizing current ceases to flow |
| C. | At the time the magnetic particles are applied to the part |
| D. | Just prior to current reversal |
| Answer» D. Just prior to current reversal | |
| 377. |
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. | Between 0 and 10 for all ferromagnetic materials |
| D. | Dependent upon the amount of magnetizing force necessary to overcome |
| Answer» A. A fixed value depending upon the type of material | |
| 378. |
The flux density of the magnetism induced by a coil is affected by: |
| A. | The coil size |
| B. | The current in the coil |
| C. | The number of turns in the coil |
| D. | All of the above |
| Answer» D. All of the above | |
| 379. |
How many turns of a coil will be needed to establish a longitudinal field in a steel shaft that is 22.86 cm (9 inches) long and 7.62 cm (3 inches) in diameter? 3000 amperes magnetizing current is available, it is desired to magnetize the part in accordance with the formula NI = 45,000/(L/D): |
| A. | 1 |
| B. | 3 |
| C. | 5 |
| D. | 7 |
| Answer» C. 5 | |
| 380. |
How many ampere-turns are required to magnetize a part that is 40.6 cm (16 inches) long and 5 cm (2 inches) in diameter? |
| A. | 9000 ampere-turns |
| B. | 5625 ampere-turns |
| C. | 2812 ampere-turns |
| D. | None of the above |
| Answer» B. 5625 ampere-turns | |
| 381. |
The lines of flux or force in a circularly magnetized ferromagnetic bar: |
| A. | Are aligned through the piece from the south to the north pole |
| B. | Are aligned through the piece from the north to the south pole |
| C. | Leave the south pole and enter the north pole |
| D. | Are contained within and around the part |
| Answer» D. Are contained within and around the part | |
| 382. |
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. | None of the above |
| Answer» D. None of the above | |
| 383. |
Which of the following is false concerning a magnetic field in and around a hollow conductor as compared to that of a solid conductor of the same outside diameter when both are of the same magnetic material, and when the applied current is the same? |
| A. | The field immediately outside the outer surface of the hollow conductor is greater |
| B. | The field gradient inside the hollow conductor is steeper |
| C. | The fields outside the conductors are the same |
| D. | The fields are the same at the centre |
| Answer» C. The fields outside the conductors are the same | |
| 384. |
The field in a section of ferromagnetic pipe being magnetized by means of a central conductor is strongest at the: |
| A. | Ends of the pipe |
| B. | Outer surface of the pipe |
| C. | Inner surface of the pipe |
| D. | The field is uniform at all places |
| Answer» C. Inner surface of the pipe | |
| 385. |
For a 7.6 cm (3 inches) diameter bar how much current is needed to magnetize the bar for the detection of longitudinal discontinuities: |
| A. | 5500 amperes |
| B. | 16500 amperes |
| C. | 1000 amperes |
| D. | 3000 amperes |
| Answer» D. 3000 amperes | |
| 386. |
For detection of longitudinal discontinuities a 7.6 cm (3 inches) diameter bar is magnetized in: |
| A. | The longitudinal direction |
| B. | The circular direction |
| C. | The clockwise direction |
| D. | None of the above directions |
| Answer» B. The circular direction | |
| 387. |
A bar that is 5 cm (2 inches) by 10 cm (4 inches) by 30.5 cm (12 inches) is being magnetized in the circular direction. About how many amperes are required using the perimeter approach? |
| A. | 2200 |
| B. | 4500 |
| C. | 3800 |
| D. | None of the above |
| Answer» C. 3800 | |
| 388. |
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 |
| Answer» D. All of the above | |
| 389. |
When a magnetic field cuts across a crack: |
| A. | Electrons begin jumping back and forth across the crack |
| B. | The crack begins to heat up |
| C. | Magnetic poles form at the edges of the crack |
| D. | All of the above |
| Answer» C. Magnetic poles form at the edges of the crack | |
| 390. |
A disadvantage of AC current is that it: |
| A. | Cannot be used with dry powder |
| B. | Has poor penetrating power |
| C. | Can only provide low flux densities |
| D. | Cannot be used for residual magnetic particle testing |
| Answer» B. Has poor penetrating power | |
| 391. |
What causes a leakage field in a steel bar? |
| A. | A crack |
| B. | Reversal of the magnetic field |
| C. | Paint on the surface |
| D. | All of the above |
| Answer» A. A crack | |
| 392. |
An indication is a defect under which of the following conditions? |
| A. | If it is greater than 3.8 cm (1.5 inches) long |
| B. | If it exceeds the limits of a standard or specification |
| C. | If it is deep |
| D. | Under all of the above indications |
| Answer» B. If it exceeds the limits of a standard or specification | |
| 393. |
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 flux lines |
| C. | The crack is sharp and the paint is thin |
| D. | All of the above |
| Answer» C. The crack is sharp and the paint is thin | |
| 394. |
A magnetic particle indication is sharp and very fine; this suggests that the discontinuity is: |
| A. | Subsurface seam |
| B. | A shallow, tight surface crack |
| C. | Porosity |
| D. | A deep crack |
| Answer» B. A shallow, tight surface crack | |
| 395. |
Among the following, the best type of current for the detection of fatigue cracks is: |
| A. | Half-wave direct current |
| B. | Alternating current |
| C. | Direct current |
| D. | Half-wave alternating current |
| Answer» B. Alternating current | |
| 396. |
Continuous magnetization provides the most sensitivity because: |
| A. | The magnetic particles are present while the part is being magnetized |
| B. | The magnetic field is greatest while the magnetizing current is on |
| C. | All of the above |
| D. | Neither of the above |
| Answer» C. All of the above | |
| 397. |
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 |
| Answer» C. Perpendicular to the direction of the magnetic flux | |
| 398. |
To provide reliability and reproducibility in magnetic particle testing, written procedures should include: |
| A. | Location of the coil and current for each magnetization |
| B. | Requirements for ammeter calibration |
| C. | Type and concentration of the particles |
| D. | All of the above |
| Answer» D. All of the above | |
| 399. |
The magnetic particles are noticed to bunch in some fillet areas and stand on end on the edge of a part being magnetized. These observations indicate that the: |
| A. | Particle concentration is too low |
| B. | Flux density is excessive |
| C. | Flux density is too low |
| D. | Magnetizing current should be changed form AC to DC |
| Answer» B. Flux density is excessive | |
| 400. |
Flux density is a measure of the number of magnetic flux lines perpendicular to an area of cross-section. If a discontinuity is in the plane of the unit area, the strongest magnetic article indication will be formed when the discontinuity is: |
| A. | Inclined at 45º to the flux lines |
| B. | Parallel to the flux lines |
| C. | 90º to the flux lines |
| D. | 135º to the flux lines |
| Answer» C. 90º to the flux lines | |
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