When a coil's magnetizing force is applied to a ferromagnetic material, the flux density in the material is:

When a coil's magnetizing force is applied to a ferromagnetic material, the flux density in the material can be greater than the flux density generated by the test coil itself, which is due to the material's magnetic properties. Ferromagnetic materials have high permeability, which allows them to easily become magnetized and considerably enhance the magnetic field.

This property results in a phenomenon known as magnetic saturation, where the material can concentrate the magnetic field lines significantly more than what is being provided by the coil. As a result of this effect, the flux density within the ferromagnetic material tends to exceed the flux density produced solely by the test coil, leveraging the material's capability to direct and amplify the magnetic field.

Understanding this principle is critical in Eddy Current Testing, where assessing the magnetic influence on defect locations within ferromagnetic materials can vastly improve the detection and characterization of flaws present. Recognizing the relationship between the coil's magnetizing force and the resultant flux density in the material is essential for interpreting test results and improving testing techniques.