What Does Electromagnetic Resistivity Test Mean?
An electromagnetic resistivity test is conducted to measure ground conductivity by electromagnetic induction. An alternating current (AC) of known frequency and magnitude is passed through the transmitting coil creating a primary magnetic field in the soil around the coil. The eddy currents generated induce a secondary current in underground conductors creating a secondary magnetic field picked up by the receiving coil that can be distinguished from the primary field by a phase lag.
The ratio of the magnitude of both these currents gives an indication of the electromagnetic conductivity in the area.
