How can magnetic permeability be measured using ET?

Magnetic permeability can be effectively measured using eddy currents, which is why analyzing the response of eddy currents is the correct approach. In eddy current testing (ET), when a conductive material is subjected to an alternating magnetic field, eddy currents are induced within the material. The characteristics of these induced currents—such as their magnitude and phase shift—are influenced by the magnetic permeability of the material.

The greater the magnetic permeability, the more easily magnetic lines of force can penetrate the material, thereby affecting how the eddy currents behave. By analyzing the response of the eddy currents, which includes measuring their amplitude and phase relative to the excitation signal, one can infer various properties of the material, including its magnetic permeability.

Other methods, such as direct measurement of dimensions, temperature measurements, or testing voltage levels, do not provide the necessary information to gauge magnetic permeability in the context of eddy current testing. Direct measurement of dimensions pertains more to the physical size and shape rather than magnetic properties. Similarly, temperature measurements can affect the electrical properties of materials but do not directly relate to magnetic permeability. Voltage level testing does not yield specific insights into magnetic properties under the approach utilized in eddy current testing. Hence, option C stands out as the