  In Feynman's lectures there is a remark about the limiting value of the
impedance of an n-section ladder consisting of purely reactive elements
(capacitances and inductances). The remark is that this limiting impedance
$z=\lim_{n\to\infty}z_n$ has a positive real part. He notes that this is
surprising since the real part of each $z_n$ is zero, therefore it is
impossible for the limit to have a positive real part. A recent article in this
journal offered an explanation of this paradox based on the fact that realistic
impedances have a non-negative real part, but the authors noted that their
argument was incomplete. We use the same physical idea, but give a simple
argument which shows that the sequence $z_n$ converges like a geometric series.
We also calculate the finite speed at which energy is propagated out into the
infinite ladder.
