1. The problem statement, all variables and given/known data 13 equal charges, q, are situated at the corners of a regular tridecagon. What is the net force on a test charge, Q, situated at the centre. 2. Relevant equations F=k(qQ/r^2) r^ (r^=r vector/r) 3. The attempt at a solution The net force will be zero due to the symetry of the tridecagon.