1) how does the electric force between two oposite charges changes when the distance between the charges is tripled?

Question

2)how does the electric force between two oposite charges changes when the amount of one charge is doubled?

Answer 1

k Q1 Q2 / d^2

1) if d2 = 3 d 1
then 1/d^2^2 = 1/(3d1)^2 = (1/9) 1/d1^2

2) k Q1 (2 Q2)/d^2 = twice original