The resistivity is independent of specimen geometry but related to R through the expression:p= RA I is the distance between the two points at which the voltage is measured,and A is the cross-sectional area perpendicular to the direction of the current [Q*m] Substituting: V=IR=1. VA Variable resistor Schematic representation of the apparatus used to Ameter Battery measure electrical resistivity Crosssectional Specimen area,A VoltmeterThe resistivity is independent of specimen geometry but related to R through the expression: 𝜌 = 𝑅𝐴 𝑙 l is the distance between the two points at which the voltage is measured, and A is the cross-sectional area perpendicular to the direction of the current [Ω*m] Substituting: 𝑉 = 𝐼𝑅 = 𝐼 ∙ 𝜌𝑙 𝐴 𝜌 = 𝑉𝐴 𝐼𝑙 Schematic representation of the apparatus used to measure electrical resistivity