Interactive Simulator · Electricity

What sets a wire's resistance

Resistance is not just a property of a component, it follows from the shape and material of the conductor: R = ρL/A. Stretch the wire longer and R rises; make it thicker (more area) and R falls; swap the material and the resistivity ρ changes everything. The resistance is read out live as you reshape the wire.

Mission Make the resistance as large as you can: long, thin, and a high-resistivity material like nichrome. Streak 0Best 0
For a given material, the resistance of a wire is:
material · resistivity ρCopper · 1.7 × 10⁻⁸ Ω m
length L1.0 m
cross-sectional area A0.50 mm²
resistance R = ρL/A0.034 Ω
Resistance rises with length (longer path) and falls with cross-section (more paths in parallel); the material sets ρ.