Two long parallel wires are located in a poorly conducting
medium with resistivity p. The distance between the axes of the
wires is equal to 1, the cross-section radius of each wire equals a.
In the case a <1 find:
(a) the current density at the point equally removed from the axes
of the wires by a distance r if the potential difference between the
wires is equal to V;
(b) the electric resistance of the medium per unit length of the
wires.