The next formula is used to calculate the conductance of a wire as a function of its length, cross–sectional área and nature of the material.

**Formula 1 **

G = x.(S/L)

**Where: **

G is the conductance in siemens (S)

X is the specific conductance or conductivity of the material in m/S

S is the corss-sectional area in square milimeters (mm^{2})

L is the length im meters (m)

**Derivated Formulas **

**Formula 2 **

S = G. (L/x)

**Formula 3 **

L = x.(S/G)

**Application Example: **

What is the conductance of a piece of aluminium wire 2 meters long and with a cross-sectional ara of 1 mm^{2}?

**Data:**

X = 34,4 m/S (specific conductance for aluminium)

L = 2 m

S = 0,1 mm2

G = ?

**Using formula 1: **

G = 34,4 x 0,1/2 =1,72 Siemens