The physical quantity which is reciprocal of resistance is-

The correct answer is Option (3) → Conductance

The conductance of a conductor is the reciprocal of its resistance, \( G = 1/R \), measured in siemens (\( \Omega^{-1} \)).

Option (1) Conductivity — Incorrect. Conductivity \( \sigma = 1/\rho \) is the reciprocal of the resistivity, a property of the material, not of a particular conductor.

Option (2) Resistivity — Incorrect. Resistivity \( \rho = RA/l \) is a property of the material and has the unit \( \Omega\,\mathrm{m} \), not \( \Omega \).

Option (3) Conductance — Correct. \( G = 1/R \).

Option (4) Current density — Incorrect. Current density is the current per unit area, \( J = I/A \), in \( \mathrm{A\,m^{-2}} \).