What is meant by "probe impedance" in Eddy Current Testing?

Probe impedance in Eddy Current Testing refers to the opposition to electric current flow that is generated by eddy currents within the material being tested. When the probe generates an alternating magnetic field, this field induces eddy currents in the conductive material. The probe's impedance is affected by both the structure of the probe itself and the characteristics of the material it is measuring, such as its electrical conductivity and the presence of defects or changes in geometry.

Higher levels of eddy currents may lead to changes in the probe impedance, which can be used to assess material properties and identify defects. Thus, understanding probe impedance is crucial for interpreting the results of an Eddy Current test accurately.

The other choices do not encapsulate the meaning of probe impedance effectively. Options referring to resistance of the testing material, the range of frequencies used, or the size of the probe coil do not capture the complexity of how probe impedance operates within the context of Eddy Current Testing.