The resistivity p of a material may be expressed in units of

The electrical resistivity (ρ) of a material is a fundamental property that quantifies how strongly it opposes electric current. According to the resistance formula, R = ρ(l/A), where R is resistance, l is length, and A is the cross-sectional area [4]. Rearranging this gives ρ = RA/l. In the SI system, the unit is ohm-meter (Ω·m) [5]. However, when lengths are measured in centimeters (cm) and area in square centimeters (cm²), the unit becomes (ohm × cm²) / cm, which simplifies to ohm-centimeter (Ω·cm) [5]. This unit is commonly used in semiconductor physics and material science to express volume resistance. While 'ohm' is the unit for resistance [2], and 'ohm/cm' or 'ohm-cm²' are incorrect dimensional representations, 'ohm-cm' is a standard and widely accepted unit for resistivity [5].

Sources

1. [4] https://www.epa.gov/environmental-geophysics/electrical-conductivity-and-resistivity
2. [1] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > What you have learnt > p. 192
3. [5] https://www.britannica.com/science/resistivity
4. [2] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > Figure 11.3 > p. 176