Electrical conductivity describes how easily an electric current can flow through a material. Conductors, materials with high conductivity, allow electricity to pass through them with minimal resistance. Copper is widely recognized as an excellent electrical conductor, making it a preferred choice for efficient electricity transmission.
Understanding Electrical Conductivity in Copper
Copper’s effectiveness as an electrical conductor stems from its atomic structure. Metals, including copper, contain electrons not tightly bound to individual atoms. These free electrons form a “sea” that can move throughout the material. In a copper atom, the outermost electron, or valence electron, is weakly held by the nucleus. This allows it to readily break away from its parent atom and become a free electron.
When an electrical voltage is applied across a copper wire, these numerous free electrons are compelled to move in a directed flow, creating an electric current. This results in copper having low electrical resistivity, meaning it offers minimal opposition to the flow of electrons. Copper’s electrical resistivity at 20 °C is approximately 16.78 nΩ•m, which indicates its high conductivity.
Copper’s Place Among Conductors
While copper is an excellent conductor, silver holds the distinction as the most electrically conductive metal. Silver’s conductivity is roughly 7% higher than copper’s, with copper having a conductivity of 59 x 10^6 siemens/meter compared to silver’s 63 x 10^6 siemens/meter. Gold ranks third in conductivity, performing less efficiently than copper. Aluminum also conducts electricity, but it has about 61% of copper’s conductivity.
Despite silver’s superior conductivity, copper is the more widely used material for most electrical applications. The primary reason for this preference is cost; silver is a precious metal, making it economically impractical for large-scale use. For instance, 1kg of silver costs around £700, while 1kg of copper is about £6-7.
Copper also possesses other practical properties. It is highly ductile and malleable, easily drawn into wires and shaped. Copper exhibits good resistance to corrosion, forming a protective film that prevents degradation, unlike aluminum which can form an insulating oxide layer. Furthermore, copper has higher tensile strength and better heat tolerance than aluminum, important for safety and durability in electrical systems. These attributes make copper a balanced and effective material.
Where Copper Conducts
Copper’s combination of high conductivity, durability, and cost-effectiveness makes it widely used across various electrical applications. Nearly half of all mined copper is used for electrical wire and cable conductors. It is a standard material for electrical wiring in homes and buildings, where its flexibility and ability to carry significant loads without overheating are valued.
In the electronics industry, copper is extensively utilized in printed circuit boards (PCBs), connectors, and terminals. Its ability to dissipate heat efficiently helps prevent overheating in electronic devices. Copper also plays a role in power generation, transmission, and distribution systems, including underground transmission lines where its electrical and thermal conductivity are beneficial. Electric motors frequently incorporate copper windings or rotors due to its superior conductivity, which reduces electrical losses and improves motor efficiency.