The impedance diagram principle states that to test all frequencies, what must lie at the same point on the diagram?

The impedance diagram principle is crucial in understanding how eddy current testing operates across different frequencies. When performing tests on conductive materials using eddy current techniques, it is essential that the frequency ratio remains consistent for a comprehensive analysis of the specimen's response. This means that at various frequencies, the impedance characteristics of the material must align, allowing for effective comparisons and interpretations of the data collected.

Maintaining the frequency ratio at the same point on the impedance diagram ensures that the responses generated by the test specimen can be accurately assessed and correlated, regardless of the changing frequency. This principle allows the technician to analyze how the material behaves under different conditions and to leverage that information for quality assurance or defect detection.