Magnetic Particle Inspection Level 2 Practice Exam

If one-inch and two-inch diameter bars were magnetized by passing the same current through them, the magnetic fields would be:

1. The same for both

2. Stronger in the two-inch diameter bar

3. Weaker in the one-inch diameter bar

4. Stronger in the one-inch diameter bar

The correct answer is: Stronger in the one-inch diameter bar

When current is passed through a conductive material to create a magnetic field, the strength of that field is influenced by several factors, including the cross-sectional area of the material. In this scenario, the one-inch diameter bar has a smaller cross-sectional area compared to the two-inch diameter bar. Although the same current is being applied to both bars, the smaller diameter of the one-inch bar results in a higher current density. Current density is defined as the amount of current flowing per unit area of cross-section. Since the one-inch bar has a smaller area, the current density is more concentrated, leading to a stronger magnetic field according to Ampere's law. This principle highlights that magnetization is affected not only by the current but also by the physical dimensions of the material through which the current flows. Thus, the magnetic field generated in the one-inch diameter bar will indeed be stronger compared to that in the two-inch diameter bar, due to the increased current density in the smaller diameter bar. So, in this context, the statement about the one-inch diameter bar having a stronger magnetic field is substantiated by the relationship between current, area, and magnetic field strength.