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Resistance and Resistivity
Electrical resistance and resistivity
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Electrical resistance of an electrical conductor depends on
- the length of the conductor
- the material of the conductor
- the temperature of the material
- the cross-sectional area of the conductor
and can be expressed as
R = ρ l / A (1)
where
R = resistance (ohms, Ω)
ρ = resistivity (ohm meter, Ω m)
l = length of conductor (m)
A = cross-sectional area of conductor (m2)
Resistivity of some Common Conductors
- Aluminum: 2.6 x 10-8 Ω m
- Copper: 1.7 x 10-8 Ω m
Resistivity of some Common Insulators
- Glass: 1 x 1010 Ω m
- Mica: 1 x 1013 Ω m
Example - Resistance
The resistance of a 10 meter copper wire with a cross sectional area of 0.8 mm2 can be calculated as
R = (1.7 x 10-8 Ω m) (10 m) / ((0.8 mm2)(10-6 m2/mm2))
= 0.21 Ω
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Related Topics
- Electrical - Amps and electrical wiring, AWG - wire gauge, electrical formulas, motors and units
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Related Documents
- Conductors - Conductors and conductivity
- Kirchhoff's Laws - Kirchhoff's current and voltage laws
- Parallel Circuits - Resistors connected in parallel
- Potential Divider - Output voltage from a potential divider
- Resistivity, Conductivity and Temperature Coefficients for some Common Materials - Resistivity, conductivity and temperature coefficients for some common materials as silver, gold, platinum, iron and more - Including a tutorial explanation of resistivity and conductivity
