Electrical Resistance
Definition
The opposition to current flow in an electrical circuit, measured in ohms (Ω). Resistance depends on material resistivity (ρ), conductor length (L), and cross-sectional area (A): R = ρL/A.
Practical Note
Copper has low resistance (~1.7×10⁻⁸ Ω·m), making it ideal for wiring. Resistance increases with temperature for metals. A 10 AWG copper wire has about 1 Ω per 1000 ft.
Related Calculators
Calculate voltage, current, resistance, or power using Ohm's Law. Enter any two known values to solve for the remaining electrical properties with animated circuit visualization.
Calculate voltage drop and power loss in electrical circuits. Recommend optimal AWG wire sizes for DC, single-phase, and three-phase systems.
Determine correct wire size based on current load and NEC ampacity tables. Applies temperature correction, conduit fill derating, and continuous load factors.