How does the electric force between two charged particles change if the distance between them is increased by a factor of 3? a. it is reduced by a factor of 3 b. it is increased by a factor of 3 c. it is increased by a factor of 9 d. it is decreased by a factor of 9

D. it is decreased by a factor of 9.

Force = kqq : r^2

The distance is squared so if it is increased or decreased by any factor, then it must be squared too. Because the distance is on the bottom of the equation, you divide the force by the increasing or decreasing factor.