The electrostatic force between two point charges in free space is 'F'. If a dielectric slab of relative permittivity 'ɛr' is inserted in their free space, then this force between the charges will

Explanation

When a dielectric slab is inserted between two point charges, it polarizes in response to the electric field created by the charges. This polarization reduces the effective electric field between the charges, which in turn decreases the electrostatic force calculated using Coulomb's law. The relative permittivity 'ɛr' quantifies this effect, with higher values indicating greater ability to reduce the electric field. Therefore, the correct answer is that the force will decrease.Option A (Increase) is incorrect because adding a dielectric does not enhance the force; it diminishes it. Option C (Remain constant) is incorrect as the presence of the dielectric modifies the electrostatic interaction. Option D (Vary unpredictably) is also incorrect since the effects of the dielectric are well-defined based on its properties.