Resistance: Metric Units

The design of resistive elements for various areas of application, including thin-film resistors and integrated circuits, uses metric units for the quantities of Eq. (1). In SI units, the resistivity would be measured in ohm-meters, the area in square meters, and the length in meters. However, the meter is generally too large a unit of measure for most applications, and so the centimeter is usually employed. The resulting dimensions for Eq. (1) are therefore
$$\rho : \text{ ohm-centimeters}$$ $$l : \text{ Length(centimeters)}$$ $$A : \text{ square centimeters}$$ The units for $\rho$ can be derived from $$\rho ={RA \over l }= {Ωcm^2 \over cm} = Ωcm$$