Why is wood a poor conductor of heat compared to metal?

• A. Because it has free electrons
• B. Because of its structure and air pockets
• C. Because it is very heavy
• D. Because it reflects heat

Answer: (B)

Heat moves through materials mainly by conduction. Metals conduct heat well because their free electrons can transfer energy rapidly from the hot side to the cold side. Wood conducts heat poorly because its structure contains lots of air-filled spaces and cellulose fibers that don’t transfer energy well. Those air pockets break up continuous paths for heat to flow, and air itself is a poor conductor, so heat moves through wood much more slowly than through metal. The other ideas don’t fit as the main reason: free electrons are a feature of metals, not wood; heaviness doesn’t determine how easily heat travels through a material; and reflecting heat concerns surfaces, not the way heat travels inside the material.