The force between two 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 force

* k is Coulomb's constant

* q1 and q2 are the charges

* r is the distance between the charges

If you quadruple the distance (r becomes 4r), the force becomes:

F' = k * (q1 * q2) / (4r)² = k * (q1 * q2) / 16r²

Therefore, the force becomes 1/16th of its original value.