Define resistivity and state its units
The resistivity of a conductor, multiplied by length (along the current direction) and divided by cross sectional area equals resistance.
The units of resistivity are ohm-meters (ohm-centimeters are frequently used also)
Resistivity is a fundamental property of a material that quantifies its ability to resist the flow of electric current. It is denoted by the symbol ρ (rho).
The resistivity of a material depends on its intrinsic properties, such as the number of free electrons and the configuration of its atomic structure. It is a measure of how strongly a material opposes the flow of electric current when a potential difference is applied across it.
The units of resistivity depend on the system of units used. In the International System of Units (SI), the unit of resistivity is ohm-meter (Ω⋅m). Using this unit, resistivity is defined as the resistance (in ohms) of a wire having a length of one meter and a cross-sectional area of one square meter. However, other unit systems, such as the CGS (centimeter-gram-second) system, use different units for resistivity, such as ohm-centimeter (Ω⋅cm).