1. The problem statement, all variables and given/known data The Electric field lines in an X-Y plane are given in the attached image. The field is defined as E=αi(vector)y at x=0 and x=some distance along the positive X axis. α is a positive constant. Test for charges in the X-Y plane 2. Relevant equations N/A 3. The attempt at a solution The diagram is attached below showing the field lines in the X-Y plane. I understand that the electric field is dependent upon the y axis only, but am having a tough time figuring out the "test for charges" Perhaps there is a way to describe the charge in equation form? I already solved the "more difficult" 2nd part of the question - go figure :rofl: A hint I was given was to "draw field lines from a charge". I feel like this is ridiculously simple and I'm missing something silly. Thanks as always!