Valero Mechanical Aptitude Practice Test

Which material is considered a good conductor?

Copper Plastic Wood Glass

Correct Answer:

Copper

Explanation:

Electric conduction happens when electrons can move freely through a material. In metals, outer electrons are loosely bound and become delocalized, forming a sea of charge carriers that can flow when a voltage is applied. Copper stands out because it has a high density of these free electrons and low resistivity, so electric current passes through it with minimal resistance. That combination—many mobile electrons and low resistance—is why copper is widely used for wiring and electrical components. Materials like plastic, wood, and glass are insulators; their electrons are tightly bound and not free to move, so they resist electrical flow. So copper is the best conductor among the options.

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