Magnetic Particle Inspection Level 1 Practice Exam

What happens to surface discontinuities that disrupt the flow of magnetic flux lines?

1. They will attract magnetic particles and form a sharp visible indication

2. They will absorb magnetic particles without any indication

3. They will repel magnetic particles

4. They will have no effect on magnetic particles

The correct answer is: They will attract magnetic particles and form a sharp visible indication

Surface discontinuities that disrupt the flow of magnetic flux lines result in an attraction of magnetic particles, which creates a visible indication. This occurs because when the magnetic field encounters a discontinuity, such as a crack or void, it creates a disturbance in the magnetic flux. As a result, the magnetic field lines may concentrate at the site of the discontinuity, leading to an accumulation of magnetic particles. This attraction is crucial for Magnetic Particle Inspection (MPI) because the particles gather at these discontinuities, enhancing their visibility under appropriate lighting conditions. This is why it is essential for inspectors to understand that visible indications directly correlate with the presence of surface defects that interrupt magnetic flux. Other options do not accurately represent the behavior of magnetic particles in relation to surface discontinuities; no repulsion or absorption without indications occurs in the case of disrupted flux lines. The process relies on the attraction of the particles to highlight and identify defects effectively.