الفهرس 
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Abstract
n geophysical investigations for mineral and water exploration, and depth determinations of the subsurface layers, electrical resistivity methode are used to obtain, quickly and economically, details about location, depth and layer resistivities. By inserting a controlled electric current into ground through electrodes and measuring its resistance, it is possible to obtain quantitive electrical data that enable calculations to be made to determine the average resistivity of the section of the investigated ground.
As a matter of fact any subsurface variation in conductivity alters the form of the current flow within the earth and this in turn affects the distribution of electric potential. The degree to which the potential at the surface is affected depends on the type, size, shape, location and electrical resistivity of the subsurface ground masses.
It is possible to obtain information about the subsurface distribution of these bodies from potential measurements made at the surface.
Current injected into the ground by means of two eletrodes and the potential DROP between a second pair of electrodes. placed within the vicinity of these electrodes are measured. from the magnitudes of the potential drop, current and electrode configuration geometry, a quantity known as ”the apparent resistivity” can be calculated. If the ground in electrically.