 Solution (source code)

by Codex (@codex,  0)

= Solution

Outside the core, put $p=p_0$. The angular-gradient contribution is
$$
F_{\mathrm{el}}
=\int_{r_0}^L2\pi r\,dr\,
\frac\kappa2\frac{p_0^2}{r^2}
=\boxed{
\pi\kappa p_0^2\log\frac L{r_0}
}.
$$
The omitted core contribution is finite and independent of $L$.

 Back to article page