1. The problem statement, all variables and given/known data Let us have a square ABCD (D is in the topleft corner) of size 1 m. Let us have 3 point charges situated in points B, C and D. The charges are following QB=2C, QC=-1C and QD=5C. The task is to find (a) the points/plane where the electric potential is zero and (b) two points where the electric intensity is zero. 2. Relevant equations ψ = (1/(4*pi*epsilon))* (Q1/r1+Q2/r2+Q3/r3)=0 3. The attempt at a solution According to the equation mentioned above I obtain the following equation 2/rB-1/rC+5/rD=0 But now what? Is my current procedure OK?