Induced polarization is a geophysical imaging

Geophysical imaging

Geophysical imaging is geophysical technique that investigates the subsurface. There are many different kinds of imaging techniques, all which are based on applied physics.Types of geophysical imaging include:...

 technique used to identify subsurface materials, such as ore

Ore

An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....

. The method is similar to electrical resistivity tomography

Electrical resistivity tomography

Electrical resistivity tomography or electrical resistivity imaging is a geophysical technique for imaging sub-surface structures from electrical measurements made at the surface, or by electrodes in one or more boreholes. It is closely related to the medical imaging technique electrical...

, in that an electric current

Electric current

Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

 is induced

Electromagnetic induction

Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

 into the subsurface through two electrode

Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

s, and voltage

Voltage

Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...

 is monitored through two other electrodes.

Time domain IP methods measure the voltage decay or chargeability over a specified time interval after the induced voltage is removed. The integrated

Antiderivative

In calculus, an "anti-derivative", antiderivative, primitive integral or indefinite integralof a function f is a function F whose derivative is equal to f, i.e., F ′ = f...

 voltage is used as the measurement.

Frequency domain IP methods (see Spectral Induced Polarisation

Spectral Induced Polarisation

Spectral induced polarisation or Complex resistivity is a geophysical survey technique and an extension of the induced polarisation method, being itself an extension of measuring the Earth's resistance at a single frequency or under direct current . SIP measures the frequency-dependent Spectral...

) use alternating current

Alternating current

In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....

s (AC) to induce electric charges in the subsurface, and the apparent resistivity is measured at different AC frequencies.

External links

• http://www.l-gm.de/English/Resistivity_Meters/resistivity_meters.html Example IP equipment and image results