Electric Field in Coaxial Cable

CL39

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?