Which one of the following correctly represents the SI unit of resistivity?

The electrical resistivity (ρ) of a material is a fundamental property that quantifies how strongly it opposes the flow of electric current. According to the mathematical relationship derived from Ohm's law, the resistance (R) of a uniform metallic conductor is directly proportional to its length (l) and inversely proportional to its area of cross-section (A), expressed as R = ρ(l/A). Rearranging this formula gives ρ = RA/l. Substituting the SI units for resistance (ohm, Ω), area (square meters, m²), and length (meters, m), the unit for resistivity becomes (Ω × m²) / m, which simplifies to ohm-meter (Ω m) [1]. While ohm-centimeter is sometimes used in specific contexts, the standard SI unit is the ohm-meter. Therefore, option 4 correctly represents the SI unit of resistivity.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > Activity 11.3 > p. 178