What is the term used to define a system that indicates only the magnitude of variations in total coil impedance?

The term that describes a system indicating only the magnitude of variations in total coil impedance is "impedance magnitude system." This system focuses on quantifying how the total impedance – the combination of resistance and inductive reactance – changes in response to different conditions, such as the presence of defects or changes in material properties.

In Eddy Current Testing, understanding variations in impedance is crucial for detecting flaws, as these variations can provide insights into material integrity. The emphasis on magnitude without considering phase information or vector analysis simplifies the interpretation process, making it easier to assess the severity of any detected variations. Such a system enables technicians to reliably determine the extent of changes in coil impedance, which is a fundamental part of evaluating the performance and reliability of components in various applications.