Top 1000+ Solved Non Destructive Testing and Evaluation MCQ Questions Answer
Q. 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
Q. 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
Q. 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
Q. 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
Q. Fields generated in ferromagnetic material with AC current are useful for locating:
a. All discontinuities
b. Surface cracks
c. Subsurface discontinuities
d. Internal porosity
Q. The formula, NI = 45000/(L/D), gives proper magnetising current for a coil, regardlessof 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
Q. What is the magnetic field strength at the surface of a 100 mm diameter bar as comparedto 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
Q. The important difference between AC and DC current for magnetic particle testingpurposes 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
Q. 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
Q. 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
Q. The formula, NI = 45000/(L/D), is used to calculate the proper magnetising currentfor:
a. Prod magnetization
b. A head shot
c. A central conductor
d. Coil magnetisation
Q. For direct contact magnetising methods, the magnetic field is oriented in what directionrelative to the current direction?
a. Parallel
b. At 45 degrees
c. At 90 degrees
d. At 180 degrees
Q. For direct contact magnetising methods, current should be flowing in what directionrelative to expected discontinuities?
a. Parallel
b. At 45 degrees
c. At 90 degrees
d. At 180 degrees
Q. What is the magnetic field strength at the surface of a 25mm diameter bar as comparedto 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
Q. 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