Question

Say you have two perfect conductors as a coaxial cable where you have an inner solid cylinder core and an outer cylindrical shell. If current runs down the inner core and returns along the outer shell what would be the advantages of have a system like this (with the coaxial cable) as opposed to a system where there are two perfect parallel conductors and current flows down one and returns via the other. Also why would twisted pairs work better than a coaxial cable?

Answer 1

in conventional parallel conductor system, the parallel conductors are exposed to the interference from the nearby current carrying wire so the current in the wires get distorted and we will not be able to achieve our desired result,whereas in coaxial cable there is a insulation surrounding the central cable which acts a buffer and protects the central conductor from outside interference from nearby wire.

however , twisted pairs of cable is capable to eliminate electromagnetic interference and crosstalk. and its advantage over coaxial cable is twisted pairs are cost effective and they are easy to install compared to coaxial cable.