1. The problem statement, all variables and given/known data GIVEN: a=radius of inner electrode = 0.05 cm b=radius of outer electrode = 0.5 cm Vo = 130 V QUESTION: What is the electric field at surface of the inner electrode in units of V/m? 2. Relevant equations Given equations Potential at radius r b/w inner&outer electrodes is V=Vo*ln(r/a) (Eq 1) Elect field at r is E(V/m) = (1/r)*[V/ln(b/a)] Eq (2) 3. The attempt at a solution First in finding the V at surface of inner electrode, the value of r is same as a because it's at surface, so the ln (r/a) term becomes zero. So that is where I am stuck. Are the equations I am given correct?