Non-Destructive Testing (NDT) Practice Test

In impedance plane displays used in eddy current testing, what is represented on the Y-axis?

1. Resistance

2. Voltage

3. Inductive reactance

4. Capacitance

The correct answer is: Inductive reactance

In impedance plane displays utilized in eddy current testing, the Y-axis represents inductive reactance. Eddy current testing relies on the interaction of an alternating magnetic field with the conductive material, which generates eddy currents. These currents exhibit both resistive and reactive components in their impedance. The Y-axis specifically showcases the inductive reactance because it is indicative of how the induced current reacts to changes in the magnetic field due to factors such as the material's properties and geometrical features. Inductive reactance is influenced by the frequency of the applied AC signal and the inductance of the system, making it a critical factor in interpreting the eddy current signals. Understanding this aspect is crucial, as it allows the operator to differentiate between various material properties and detect flaws or inconsistencies in the tested components. Hence, the representation of inductive reactance on the Y-axis is essential for proper evaluation in eddy current testing.