The electrostatic force between two charges is 1.8 * 10-6 N when q1 = q2; that is, when the charges are equal in magnitude. If the magnitude of q1 only is now doubled, what happens to the force between them if the distance between them is not changed?

Doubled

Explanation:

F = 1.8 x 10^-6 N, q1 = q2

The force between the two charges is directly proportional to the product of two charges and inversely proportional to the square of distance between them.

Now one of the charge is doubled but the distance remains same so the force between the two charges becomes doubled.