Various materials can be used as electric conductors for transmitting energy, signals or data in cables and wires. The most well-known and commonly used one is copper (Cu) which is a very ductile metal with high conductivity. It is also flexible, high-tensile and comparatively cheap, making it the first choice for many applications. The conductor comprises either a single wire or multiple wires twisted together to form a so-called strand. Copper can be tin-plated, for example, to make it more corrosion-resistant, or nickel-plated to improve its temperature range.
Aluminium (Al) is another potential conductor material. Its major benefit over copper is a much lower density. But it has poorer conductivity which means a greater cross section is required to transmit the same current. In addition, aluminium wires are less flexible and hence more likely to break. This makes them unsuitable for moving applications. As a result, aluminium is mainly used for energy distribution cables and medium voltage cables where weight plays an important role.
The material with the best conductivity is silver (Ag) but it is many times more expensive than copper. For this reason, silver is normally only used in special applications where exceptional performance and efficiency is required – for example in high-end audio. Another possible conductor for audio cables is silver-plated copper wire which stands out for high conductivity and resistance to corrosion. The high price and poorer conductivity of gold (Au) compared to silver and copper rules this out as a conductor.
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