There are a number of electrical methods which can be used for NDT such as resistance measurement, electrical conductivity measurement, the use of tribo-electric, thermo-electric, exoelectron effects etc, one major group being eddy current testing.
All electrical methods are indirect; a material property is measured as an electrical property variation. The methods are applicable to all electrically-conducting materials.
Electromagnetism, or electromagnetic effects resulting from the interaction of electricity and magnetism, form the basis of a number of methods of NDT, including eddy current testing, magnetic particle inspection, magnetic flux leakage testing, and ACFM. Electromagnetic induction tests are applied to all stages of metal and alloy fabrication and processing.