geometric factor

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A numerical multiplier defined by the geometrical spacings between electrodes, which is used in conjunction with the voltage-to-current (R) ratio measured in electrical resistivity surveys to give an apparent resistivity (ρa) such that ρa = Kg × R. The generalized formula for calculating Kg for a four-electrode configuration is: Kg = 2π(1/C1P1 – 1/C1P2 – 1/C2P1 + 1/C2P2)1 where C1 and C2, and P1 and P2 are the current and potential electrode positions respectively. The geometric factor for the three main electrode configurations are: dipole–dipole, Kg = πn(n + 1)(n + 2)p; Schlumberger, Kg = (πp2/q)(1 – q2/4p2); Wenner, Kg = 2πp, where p and q are defined for each case.

Subjects: Earth Sciences and Geography.

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