1. The problem statement, all variables and given/known data In the circuit given (attached) , point S is earthed , what are the electrical potentials at point P , Q and R . 2. Relevant equations Kirchoff's second law . 3. The attempt at a solution The electric potential at point S is 0 . By applying Kirchoff's second law , I(2+3)=15-5 I=2A i am not sure where to go from here .