Which parameter is directly influenced by the frequency used in eddy current testing?

The frequency used in eddy current testing has a direct impact on inductive reactance. Inductive reactance is the opposition to the flow of alternating current caused by the inductance of a coil. In eddy current testing, as the frequency increases, the inductive reactance also increases, which affects the overall impedance of the coil being used.

Higher frequencies tend to generate eddy currents closer to the surface of the conductive material, while lower frequencies can penetrate deeper. This relationship allows for the tuning of the testing process, enabling the identification of defects at varying depths in the material under inspection.

Magnetic permeability, thermal conductivity, and electrical resistance do not change directly with variations in frequency in the same manner as inductive reactance does. Therefore, inductive reactance is the parameter most clearly influenced by frequency in the context of eddy current testing.