Question Corner Science

Why are there numerous thin copper strands inside an electric wire instead of a single copper strand that is as thick?

S. Udayaprakash, Karur, Tamil Nadu

Copper being a very good conductor of electricity is used extensively in electric wires and cables. To make these wires and cables more economical, the prime objective it to optimize the amount of copper per unit length that can carry certain rated current through itself without being damaged or burned.

In general, the electric power that is to be supplied to the household and most of the electric equipment of industries is AC type, i.e. ‘Alternating Current’. One of the properties of alternating current is that it has tendency to flow in the surface of any conductor. It means the flow of alternating current is highly concentrated near the circumference instead of being evenly distributed in the whole cross-section of the conductor. This tendency is increased with the increment of frequency of alternating current. This phenomenon is called ‘skin effect’. The skin effect concludes that for flowing of the higher amount of AC requires more circumferences instead of more cross-sectional area of conductor.

Hence, instead of single copper strand, a copper wire has numerous multi-strands that increases its circumference dimension so that for the same amount of the copper, a wire of higher rated current can be manufactured. A multi-strand wire also offers more mechanical strength then a single-strand wire.

Prakhar Verma


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Printable version | Jul 29, 2021 12:43:25 AM |

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