ET ASNT Level II Practice Exam 2025 – Complete Preparation Guide

The impedance of a test coil can be accurately represented by the vector sum of inductive reactance and resistance. In an electromagnetic testing setup, such as eddy current testing, the coil has both resistive and reactive components.

Inductive reactance, which is based on the inductance of the coil and the frequency of the AC signal, represents the opposition that the coil presents to the change in current due to its inductive properties. Resistance, on the other hand, represents the inherent opposition to current flow due to the material properties of the coil itself, typically involving losses such as those due to heat.

When calculating impedance in AC circuits, it is crucial to consider both the inductive reactance, which can be visualized as contributing to the phase shift between voltage and current, and the resistive component, which affects the magnitude of current flow. The resultant impedance is a complex number, often expressed in polar form, combining both of these aspects. This understanding is vital in ensuring accurate measurements and interpretations in electromagnetic testing techniques.

While other options mention capacitance or just inductance, these do not accurately represent the primary components of the impedance in a test coil scenario relevant to eddy current applications.