The resistivity of a substance is the resistance of a wire of that substance of unit length and unit area of cross-section. Resistivity is the resistance of the flow of current from one end to the other in a material.
The resistivity is designated as ρ and it is directly proportional to the material resistance and length. Resistivity is inversely proportional to the area of cross-section of the given material. High resistivity designates poor conductors. Insulator has high resistivity.
Formula of resistivity
The formula of resistivity can be given as
ρ is the resistivity
R is the resistance
l is the length of the material
A is the area of cross-section.