Which of the following materials is commonly used as a conductor?

Copper is commonly used as a conductor due to its excellent electrical conductivity properties, which allow it to efficiently transmit electricity with minimal resistance. Its atomic structure features a high number of free electrons, facilitating the flow of electric current. Additionally, copper is relatively abundant, cost-effective, and durable, making it a preferred choice in various electrical applications, including wiring and circuitry.

In contrast, rubber, plastic, and wood are typically used as insulators rather than conductors. These materials have very few free electrons, which limits their ability to carry electrical currents. Instead, they are employed to prevent the flow of electricity, thereby enhancing safety in electrical systems by protecting against short circuits and accidental shocks.