The force between charges is inversely proportional to the square of the distance between them. This is described by Coulomb's Law:

F = k * (q1 * q2) / r²

Where:

* F is the electrostatic force

* k is Coulomb's constant

* q1 and q2 are the magnitudes of the charges

* r is the distance between the charges

If the separation distance is tripled, the new force becomes:

F' = k * (q1 * q2) / (3r)² = k * (q1 * q2) / 9r² = (1/9) * F

Therefore, the force between the charges decreases to one-ninth of its original value when the separation distance is tripled.