Assertion: The resistivity for a substance is its resistance when it is one meter long and its area of cross-section is one square meter.
Reason: The SI units of resistivity is ohm meter (m).

Assertion and Reason both are correct statements and reason is the correct explanation for assertion.

R α \(\frac{l}{A}\)

R = ρ\(\frac{l}{A}\)

ohm = ρ\(\frac{1m}{1m^2}\)

ohm m = ρ