The property of a medium which determines the electric force between two charges situated in the medium is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Permittivity
By Coulomb's law, the force between two charges in a medium depends on the permittivity \( \varepsilon \) of that medium.
\( \displaystyle F = \frac{1}{4\pi\varepsilon}\,\frac{q_1 q_2}{r^{2}} = \frac{1}{4\pi\varepsilon_0 K}\,\frac{q_1 q_2}{r^{2}} \)
In a medium of dielectric constant \( K \) the force is \( K \) times smaller than in vacuum.
Option (1) Magnetic susceptibility — Incorrect. Magnetic susceptibility describes how a material is magnetised in a magnetic field; it does not enter the force between charges.
Option (2) Permittivity — Correct. Permittivity is the only property of the medium in Coulomb's law.
Option (3) Conductivity and permeability — Incorrect. Conductivity concerns current flow and permeability concerns magnetic fields; neither fixes the electrostatic force.
Option (4) Permeability only — Incorrect. Permeability is the magnetic counterpart of permittivity; it appears in the force between currents, not between charges.