Two wires (radius a) with charge densities +λ and -λ are placed parellel to on another a distance d away. Find an expression for the potential difference between the wires and simplify with the assumption the d>>a. From that I need to find the potential difference at the midpoint between the two wires. I have figured out the E field and potential for one wire (the first part of the problem). For outside one wire, E= λ /((2pi)(eo)(r). I'm not really sure how to approach this - find the E field of this first?) Any tips would be appreciated.