What is the term for an eddy current test coil's opposition to alternating current flow?

In the context of an eddy current test coil, the term that describes the opposition to alternating current flow is impedance. Impedance is a comprehensive term that encompasses both resistance and reactance, reflecting the total opposition that a circuit element, such as a coil, presents to alternating current.

Resistance refers specifically to the opposition to current due to the material's conductive properties, whereas reactance pertains to the opposition caused by the coil's inductance or capacitance, and is frequency-dependent. In eddy current testing, the coil is primarily an inductive component, meaning it also introduces inductive reactance. However, the total opposition (impedance) includes both the actual electrical resistance and the inductive reactance.

Capacitive reactance, while related to opposition to current in capacitors, is not applicable in this case as it focuses on capacitive elements rather than inductive ones like coils used in eddy current testing. Thus, understanding impedance allows for a comprehensive view of how alternating current interacts with the coil in the test.