This method utilizes the magnetic or electromagnetic properties of the earth. There are multitude of different EM and Magnetic instrument in use by geophysicist, but they tend to work on similar concepts and principles. The electromagnetic prospecting method depends on the introduction of an oscillating electromagnetic field in the earth and the observation of the effect of this induced field at a receiving point.
The oscillating field is usually produced by some sort of coil arrangements. The generated electromagnetic waves measure the geometry, amplitudes, and phase of the electromagnetic fields at various observation locations, interpretations of these field variations, one can infer the existence of subsurface conductors, their geometry, and their depth of deposition. The magnetic method is based on evaluating the unequal distribution of magnetic forces within the earth's crust, and these anomalies are expected due to the variations in the physical properties of the rocks such as magnetic susceptibility or the remaining magnetization of the rocks
Typical applications of electromagnetic and magnetic methods include: