Magnetic Particle Inspection Level 1 Practice Exam

Where does the magnetic field produced by the use of a yoke lie?

1. Inside the test object only

2. Only on the surface of the test object

3. Inside and outside the test object

4. Around the test object

The correct answer is: Inside and outside the test object

The magnetic field produced by a yoke extends both inside and outside the test object. This occurs because the yoke, which typically consists of a pair of magnetic poles, creates a magnetic circuit that not only magnetizes the surface of the material being tested but also penetrates into it. The leakage of the magnetic field is an essential factor in magnetic particle inspection, as it aids in the detection of surface and near-surface discontinuities. In practical terms, the strength and configuration of the magnetic field can influence how well it penetrates the test object and how effectively the magnetic particles respond to it. Understanding that the magnetic field exists both inside and outside of the material is crucial for effective inspections, as it means that any cracks or defects that interrupt the magnetic field will result in a visible indication when suitable magnetic particles are applied.