Wire Resistance
Wire Resistance
Every conductor has resistance set by its material and geometry, which drives voltage drop and heating in cables.
The resistance is R = ρ·L/A. where ρ is the resistivity, L the length and A the cross-section area.
Inputs
rho := 1.68e-8 Ohm·m=1.68e-08 kg·m^3/A^2/s^3
L := 50 m=50 m
A := 2.5 mm^2=2.5e-06 m^2
Resistance grows with length and falls with area.
R := rho·L/A=0.34 Ω
Results
A longer or thinner wire has more resistance and more voltage drop. This is why long runs use thicker cable to limit losses.
Assumptions & limitations
- Uniform conductor at one temperature.
- DC (no skin effect).
- Single solid conductor.