I need to know why we require two conductors in a twisted pair cable... If one is for transmission and other for reception, how come a single copper wire in coaxial cable does both the operations...?

There are two conductors in a co-axial cable. The central core and the screen which is the return. Coaxial cable with only do one at a time, transmit or receive. That is why with a thin Ethernet co-axial cable set up you can only run at half-duplex instead of full-duplex as with Cat5 cable. With Cat5 cable there are in fact four conductors. Transmit and receive and a common ground for each which is what is twisted in with the other cables. The transit and receive cables are not twisted together. Stuart

The commonly called shield is part of the circuit. It is the return path. No on many systems you could break the shield and it sort of works or works because of other common ground or return paths. Don't get what I say as tx/rx or full duplex. I am only talking of voltage potential and how to apply it to a circuit. I read it wrong and answer it wrong too. So get off my case you goober.

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