Magnetic Particle Inspection Level 1 Practice Exam

What occurs to the magnetization current frequency when the skin effect is present?

1. Decreases

2. Remains constant

3. Increases

4. Fluctuates

The correct answer is: Increases

When the skin effect is present, the magnetization current frequency increases. The skin effect refers to the phenomenon where alternating current (AC) tends to flow near the surface of a conductor rather than uniformly throughout its volume. This effect becomes more pronounced at higher frequencies. As the frequency of the magnetization current increases, the skin depth—the depth to which the current penetrates the material—decreases. As a result, a larger portion of the magnetic field is concentrated at the surface of the material, leading to more efficient magnetic particle inspection. The increased frequency can improve the sensitivity of detecting surface and near-surface defects, making it critical for inspections in materials where precise surface integrity is essential. Thus, understanding the relationship between frequency and the skin effect is essential for optimizing magnetic particle inspection processes.