Question

How does the electrostatic force between two point charges change when a dielctric medium is introduced between them ​

Answer 1

The electrons in the dielectric will be attracted toward the positive point charge and a positive charge will be induced near the negative point charge.

Hope it helps

Answer 2

The electric force decreases by a factor of epsilon (permittivity of the medium) of the introduced medium from what it would have been in absence of all media.

F(new) = F(old)/e(of the medium introduced)