6.14 Capacitance of a Transmission Line The capacitance per meter of a single-phase, two-wire transmission line is given by the equation
$\pi \epsilon$
$C = \frac{\pi \epsilon}{\ln(\frac{D - r}{r})}$ (6.17)
where $C$ is the capacitance in farads per meter of line, $\epsilon_0 = 8.85 \times 10^{-12} F/m$
is the permittivity of free space, $D$ is the distance between the two conductors,
and $r$ is the radius of each conductor. Write a function that calculates the total
capacitance of a transmission line as a function of its length in kilometers, the
spacing between the two conductors, and the diameter of each conductor. Use