The resistance of an homogeneous conductor depends on the length, cross-sectional area and the nature of the material. The next formula is used to calculate the resistance from those quantities:
Fórmula 1
R = ρ x L/S
Where:
R = conductor´s resistance in Ω (Ω)
ρ = resistivity or specific resistance of the used material
L = length in meters (m)
S = cross sectional area in square millimeters (mm2)
Derivated Formulas:
Formula 2
L = R x S/ ρ
Formula 3
S = ρ x L/R
Application Example:
What is the resistance of a length of homogenous copper wire with a Constant cross sectionnal area of 0,5 mm2?
Data:
L = 1 m
ρ = 0,016
S = 0,5 mm2
R = ?
Applying formula 2.1:
R = 0,016 x 1 / 0,5 = 0,032 Ω
