When using the eddy current method, discontinuities are most easily detected when the eddy currents are:

In the eddy current testing method, the ability to detect discontinuities is highly influenced by the orientation of the eddy currents relative to the discontinuity itself. When eddy currents are perpendicular to the major plane of the discontinuity, this orientation enhances the likelihood of identifying disruptions in the material's structure.

This is because the flow of eddy currents will interact with the discontinuity in such a way that it creates a significant change in the impedance of the coil. When the eddy currents are perpendicular to the defect (which typically takes the form of cracks, voids, or other discontinuities), the disruption causes a greater distortion in the eddy current flow. This results in a more pronounced signal change that can be more easily detected by the testing equipment.

In summary, when the eddy currents are aligned perpendicular to the major plane of the discontinuity, they create a more effective interaction, making defect detection more reliable and efficient in the eddy current testing process.