Which material is commonly used for lightning rods?

The commonly used material for lightning rods is copper. This choice is correct because copper is an excellent conductor of electricity, which is essential for the effective functioning of a lightning rod. When lightning strikes a structure, the lightning rod provides a direct path for the electrical discharge to follow, directing it safely into the ground. Copper's superior conductivity ensures that the energy from the lightning is efficiently transmitted, minimizing the risk of fire or damage to the structure.

Additionally, copper is resistant to corrosion, making it suitable for outdoor installations where it can be exposed to various weather conditions over time. This durability adds to the longevity and reliability of the lightning protection system.

The other materials listed, such as wood, plastic, and concrete, do not possess the necessary conductive properties required for lightning rods. Wood and plastic are insulators and would not provide a safe pathway for lightning. Concrete, while somewhat conductive, does not compare to the effectiveness of copper in this application. Thus, copper remains the preferred choice for lightning rods due to its electrical properties and resistance to environmental degradation.