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 l, the cross-section radius of each wire equals a. In the case a<(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.