It is a measure of how strongly a specific material opposes the flow of electric current on resistors or conductors with a uniform cross-section, where current flows uniformly. As a reciprocal quantity, conductivity is a measure of how easy a material permits the flow of current. This are related by:
Resistivity = 1 / conductivity
The equation is:
ρ = 1 / σ
Resistivity-conductivity Formula Questions:
1) What is the conductivity of a wire of cooper?
From the resistivity-conductivity formula, we substitute the cooper resistivity which is 1.68*10(-8) Ω*m:
σ = 1/1.68*10(-8) Ω *m = 0.59 *10(8) S/m (siemens per meter)
2) A wire with a resistance of 1.53 k Ω has a length of 1 m and A= 3 cm2. What is its resistivity and conductivity?
From the electric resistance formula, we find:
ρ = R A/L = 1.53 k Ω * 0.0003 m3 / 1 m = 4.6*10(-1) Ω*m
the conductivity is, from the resistivity-conductivity relation:
σ = 1/ρ = 2.1 S/m