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( Cable)
A cable is one or more strands bound together. Electrical cables may contain one or more metal conductors, which may be individually insulated or covered. An optical cable contains one or more optical fibers in a protective jacket that supports the fibers. Mechanical cables such as wire rope may contain a large number of metal or fiber strands. In the 19th century and early 20th century, electrical cable was often insulated using cloth, rubber and paper. Plastic materials are generally used today, except for high reliability power cables. So that is how it became cable. Electrical cables may be made flexible by stranding the wires. The technical issue is to reduce the skin effect voltage drop while using with alternating currents.In this process, smaller individual wires are twisted or braided together to produce larger wires that are more flexible than solid wires of similar size. Bunching small wires before concentric stranding adds the most flexibility. A thin coat of a specific material (usually tin-which improved striping of rubber, or for low friction of moving conductors, but it could be silver, gold and another materials and of course the wire can be bare - with no coating material) on the individual wires. Tight lays during stranding makes the cable extensible (CBA - as in telephone handset cords). Bundling the conductors and eliminating multi-layers ensures a uniform bend radius across each conductor. Pulling and compressing forces balance one another around the high-tensile center cord that provides the necessary inner stability. As a result the cable core remains stable even under maximum bending stress.
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