Electronic apparatus for non-destructive testing and testing of materials; electronic apparatus for non-destructive testing of materials by means of magnetic field determination; electronic apparatus for non-destructive testing of materials by means of eddy current testing; electronic apparatus for non-destructive testing of materials by means of ultrasound measurement; electronic apparatus for non-destructive testing of materials by means of imaging methods, in particular by means of thermography; electronic apparatus for measuring electric, magnetic and other physical properties; electronic apparatus for measuring magnetic flow density and relative magnetic permeability; apparatus for testing conductive materials, in particular metallic materials, for material defects, surface defects and material inhomogeneities; electronic apparatus for measuring the magnetisation, saturation induction and coercive field strength; detectors for metallic objects; probes, sensors, test heads and exploring coils for the aforesaid apparatus; electronic data processing equipment for controlling electronic apparatus, and for evaluating information therefrom; parts of the aforesaid goods; software and programs recorded on data carriers for controlling electronic apparatus and for evaluating and presenting the information therefrom