Which of the following describes the testing method that uses an alternating magnetic field to analyze flaws?

The testing method that uses an alternating magnetic field to analyze flaws is Eddy Current Testing. This technique involves inducing eddy currents in a conductive material using a coil that generates an alternating magnetic field. When defects, such as cracks or corrosion, are present in the material, they disturb the flow of eddy currents.

The key aspect of Eddy Current Testing is its ability to detect surface and near-surface defects due to changes in the impedance of the coil as it interacts with the eddy currents. This method is widely used in the inspection of metals, particularly in applications such as aerospace and power generation where integrity is critical.

In contrast, Ultrasonic Testing relies on high-frequency sound waves to detect flaws, while Visual Inspection involves simply looking at the surface for visible signs of issues. Liquid Penetrant Testing uses a dye that seeps into surface cracks, which is then visually examined. Thus, these methods operate on completely different principles compared to Eddy Current Testing.