The resistance of a wire increases as it becomes longer and decreases as it becomes wider. (A simple analogy is a road - the more lanes there are, the less traffic there is.) The resistance R of a wire with a constant width, therefore, can be calculated as:
where is the length of the conductor, measured in meters [m], is the cross-sectional area of the conductor measured in square meters [m²], and ρ (Greek: rho) is the electrical
resistivity (also called specific electrical resistance) of the material, measured in ohm-meters (Ω m).
Calculate the resistance of copper wire with a radius of 2mm and a length of 5 meters.
- The resistivity () of copper is Ω m.
- The cross sectional area () is square meters
- The length () is meters