I know how to use the law with two particles and sometimes with three, but the way this problem is set up has me a bit confused. Use coulomb's law to find the electric force (magnitude and direction) on q for (a)q=2e-6 C and (b)q=-4e-6C. The picture is this *sorry I have to actually draw it out* (3e-6 C)--3cm---(q)---2cm--(4e-6C). How do I use Coulomb's law to find the force on a particle IN BETWEEN two particles. Also does the fact that q changes from postive to negative (part a and then part b) affect this problem?