Which materials are good conductors?

• A. Metals such as copper, gold and aluminium and electrolytes (solutions containing acids, salts and alkalis).
• B. Rubber, plastic and wood.
• C. AC current.
• D. The material has a small resistance, a current can pass freely through it.

Answer: (A)

The ability to conduct electricity depends on having plenty of mobile charge carriers. Metals provide this through free electrons that can move easily, allowing current to flow. Electrolytes contain ions that can move in solution, also carrying charge and conducting well. That combination—metals and electrolytes—explains why they are good conductors.

In contrast, rubber, plastic, and wood have few or no free charge carriers, so they resist current and act as insulators. AC current is not a material itself; it’s a type of electrical current. A material with small resistance describes a conductor in general, but it’s a property, not a specific material.