Plot a graph showing the variation of coulomb force (F) versus , where r is the distance between the two charges of each pair of charges: (1 C, 2 C) and (2 C – 3 C). Interpret the graphs obtained. 

Force between charged particles is given by, 


The graph between F and  is a straight line of slope  passing through the origin.

Magnitude of slope is more for attraction, therefore attractive force is greater than the repulsive force.