Magnetic Particle Inspection Level 1 Practice Exam

What is the term for the magnetic field strength that remains in the material after the magnetizing force is removed?

1. Residual magnetism

2. Temporary magnetism

3. Induced magnetism

4. Permanent magnetism

The correct answer is: Residual magnetism

The term that describes the magnetic field strength that remains in a material after the magnetizing force has been removed is referred to as residual magnetism. This phenomenon occurs because some materials, particularly ferromagnetic ones, retain a portion of their magnetization even after the external magnetic field is no longer applied. Residual magnetism is significant in non-destructive testing, including magnetic particle inspection, as it can impact the detection of flaws in materials. Temporary magnetism refers to materials that only exhibit magnetism while in the presence of an external magnetic field and lose their magnetization immediately after the field is removed. Induced magnetism describes the temporary magnetization that occurs when a material is exposed to an external magnetic field; it does not account for any residual magnetism after the field's removal. Permanent magnetism is associated with materials that have been magnetized in such a way that they maintain their magnetism indefinitely without an external field. Residual magnetism is distinct from these other concepts, as it specifically addresses the remaining magnetization in a material following the cessation of the external magnetizing force.