Which of the following are examples of conductors?

• A. Copper, Silver, Gold.
• B. Glass, Plastic, Wood.
• C. Copper, Plastic, Wood.
• D. Silver, Rubber, Plastic.

Answer: (A)

Electric current flows easily in materials that have free charge carriers. Metals provide a sea of delocalized electrons that can move in response to a potential difference, so they conduct well. Copper, silver, and gold are classic examples of good conductors because all three have lots of free electrons and low resistance. The other materials listed—glass, plastic, wood, and rubber—are insulators: their electrons are tightly bound and don’t move freely, so they resist electrical current. Since the question asks for examples of conductors, the all-metal option is the only one where every material listed conducts electricity.