1. The problem statement, all variables and given/known data You are given two unknown point charges, Q_1 and Q_2 . At a point on the line joining them, one-third of the way from Q_1 to Q_2 , the electric field is zero (see figure). The charges are separated by length, L. What is the ratio of the charges Q1/Q2? 2. Relevant equations F=k(Q1Q2)/r2 3. The attempt at a solution I tried to put one charge in terms of the other, but I got lost and it seemed to be going nowhere. I'm stuck..