Which of the following materials is considered an excellent conductor of electricity?

Copper is widely recognized as an excellent conductor of electricity due to its high electrical conductivity, which allows electric current to flow through it with minimal resistance. Its atomic structure facilitates the movement of free electrons, making it highly effective for transporting electrical energy. This property is particularly valuable in electrical wiring and components, where efficiency and safety are paramount. Copper's durability and resistance to corrosion further enhance its performance as a conductor in various applications, ranging from residential wiring to industrial machinery.

In contrast, rubber, plastic, and glass are classified as insulators, meaning they do not allow electricity to flow through them effectively. These materials are designed to prevent electrical currents from passing, making them essential for safety in electrical applications.