# Tow cylindrical conducting

1. Sep 7, 2009

### eman2009

1. The problem statement, all variables and given/known data

tow long cylindrical conducting wire ,each of radius a and length l parallel and separated by d , and between the centers of the wires , d>>a ,and the surface charge densities is uniformly,then the total electris potential is the sum of each wire . the effect between them is neglected .

2. Relevant equations
show the capacitance of the wire is c=pi (l) epsolen /In(d/a)

3. The attempt at a solution
I tryed to separate the electric potential for each and use gauss's law
first for Q+
v=-INT E.da
=-Q/2piepsolin l INT ds/s ,s=a
but how the limit of the INT will be
and then find the other v for the other wire with Q-
I got for c=Q/v =2 pi epsolin l /In (a+/a-)

or may be use the coulomb's law insted