How does a coaxial cable work?

That is the biggest load of rubbish of all time. ANYTHING electrical needs 2 wires or no electricity can flow. Connect a single wire to say a vacuum cleaner motor, which is how it is connected when you just plug it in, and it does not run. When you turn on the switch it connects the other wire to it to complete the circuit and offer a return path to the supply. A coaxial cable requires the exact same conditions. The screen is connected to a ground point at each end. This allows any interference signals to leak away to ground without affecting the inner core. Then the inner core has signal applied at one end and the voltage applied between the screen and the core is passed to the other end of the cable as a minimal current flow. At the receiving end the equipment reads this voltage changes and converts them into the type of signal it needs. Old computer networks used these cables and the computers interpreted the signal as command and data, then replied while the other machine waited for a reply. TV and cable services provide signals that a TV or decoding device can convert into separate video and audio signals to display and drive speakers.