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## Homework Statement

I have two coaxial infinite cylinders and I must find their capacitance, where [tex]r_{1} < r_{2}[/tex]

## Homework Equations

## The Attempt at a Solution

I got an answer (for finite cylinders) that is inversely proportional to [tex]Ln (r_{1}/r_{2})[/tex].

Assuming this answer is correct (if someone can check it), in order to make it infinite the two radii have to become infinitesimally small (0) correct? If I do this though, I get an indeterminate in the argument of log.

Have I done this wrong or must I rewrite my expression in terms of some approximate expansion?