AEA Amatrol's Sensor Logic Systems Practice Test

Inductive proximity sensors detect metal objects by the magnetic field produced by a coil. When a metal enters that field, eddy currents are generated in the object, which changes the coil’s impedance and signals its presence. Ferrous metals, like iron and steel, have high magnetic permeability, so they interact strongly with the magnetic field and cause a clear, reliable change even at practical sensing distances. Non-ferrous metals are less responsive to the field, plastics and wood are non-conductive and don’t affect the field at all, so they aren’t sensed. So the material that fits best is ferrous metal.