# geometric factor

**geometric factor (K_{g})** 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 (ρ

_{a}) such that ρ

_{a}=

*K*

_{g}×

*R*. The generalized formula for calculating

*K*

_{g}for a four-electrode configuration is:

*K*

_{g}= 2π(1/

*C*

_{1}

*P*

_{1}− 1/

*C*

_{1}

*P*

_{2}− 1/

*C*

_{2}

*P*

_{1}+ 1/

*C*

_{2}

*P*

_{2})

^{−1}where

*C*

_{1}and

*C*

_{2}, and

*P*

_{1}and

*P*

_{2}are the current and potential electrode positions respectively. The geometric factor for the three main electrode configurations are: dipole—dipole,

*K*

_{g}= π

*n*(

*n*+ 1)(

*n*+ 2)

*p*; Schlumberger,

*K*= (π

_{g}*p*

^{2}/

*q*)(1 −

*q*

^{2}/4

*p*

^{2}); Wenner,

*K*

_{g}= 2π

*p*, where

*p*and

*q*are defined for each case.

#### More From encyclopedia.com

#### NEARBY TERMS

**geometric factor**