A $60-$Hz$,$ single$-$phase two$-$wire overhead line has solid cylindrical copper conductors with a $1\mathrm{.}5$ cm diameter. The conductors are arranged in a horizontal configuration with $0\mathrm{.}5$ m spacing. Calculate in mH$/$km $($a$)$ the inductance of each conductor due to internal flux linkages only, $($b$)$ the inductance of each conductor due to both internal and external flux link$-$ages, and $($c$)$ the total inductance of the line.