A single-phase line has two conductors of equal radii r and the separation between the conductors is D. The capacitance per unit length of the transmission line will be __________ (μF/km).
1
\(\frac {\varepsilon_0}{\ln \left(\frac D r \right)}\)
2
\(\frac {0.0121}{\ln \left(\frac D r \right)}\)
3
\(\frac {0.0121}{\log \left(\frac D r \right)}\)
4
\(\frac {\pi \varepsilon_0}{\log \left(\frac D r\right)}\)