An electromagnetic method that uses electrodes with time-varying currents and voltages to map the variation of electrical conductivity in the Earth at low frequencies. It is the capacitance effect, or chargeability, exhibited by electrically conductive materials and is observed when a steady current through two electrodes in the Earth is shut off: the voltage does not return to zero instantaneously, but rather decays slowly, indicating that charge has been stored in the rocks. As a result, it is often used in exploration for minerals and can sometimes distinguish different types of mineralization

Measurement of induced polarization is done by pulsing an electric current into the earth at one or two second intervals through metal electrodes. Disseminated conductive minerals in the ground will discharge the stored electrical energy during the pause cycle. The rate of the discharge is measured by the induced polarization receiver and will be zero if there are no polarizable materials present.

Generally, both induced polarization and resistivity measurements are taken simultaneously during the survey. The depth of the survey is determined by electrode spacing - the wider the spacing the deeper the reading.