Electricity 3 Resistivity

What is resistivity?

Resistivity is an intrinsic material property that measures how strongly a material opposes electric current, independent of the conductor's dimensions.

What is the resistivity equation?

ρ=RA/L(units:Ω⋅m)

What’s the relationship between the resistance of a wire and its diameter

R∝d2​: resistance is inversely proportional to the square of the wire diameter

What’s the relationship between the resistance of a wire and its length

resistance is directly proportional to the wire length

what’s the relationship between the resistance of a wire and its area?

resistance is inversely proportional to the wire's cross-sectional area

What effect does temperature have on the resistance of a metallic conductor

Increasing temperature increases the resistance of a metallic conductor

what effect does the temperature have on the resistance of a superconductor

Increasing temperature decreases the resistance of a semiconductor

what happens when a superconductor is cooled below it’s critical temperature

When cooled below its critical temperature, a superconductor's resistance falls to exactly zero

what applications use superconductors?

Superconductors are used in MRI scanner magnets, particle accelerators, maglev trains, lossless power transmission, and SQUID magnetic sensors