When two point charges of magnitude q1 and q2

are separated by a distance, r, the magnitude of

the electrostatic force between them is F. What

would be the magnitude of the electrostatic force

between point charges 2q1 and 4q2 when

separated by a distance of 2r?

(1) F (3) 16F

(2) 2F (4) 4F

2F

Explanation:

From the Coulomb's Law, we know that the force between two point charges separated by a distance r is

As the magnitude of the charges and distance both changed in the second part of the question, the new force will be

Thus upon changing the charges and distance between the charges the magnitude of the new force will be two times the magnitude of earlier force, i.e. 2F.