Questions: Conductors and Insulators of Heat and Electricity

Question 1

A metal spoon and a wooden spoon sit in the same cup of hot soup. After two minutes, the metal spoon's handle is hot but the wooden spoon's handle is still cool. Why?

• A. The metal spoon is closer to the soup
• B. Metal is a conductor — it lets heat travel through it quickly from the soup to the handle. Wood is an insulator — it slows heat flow.
• C. The soup is hotter near the metal spoon
• D. The wooden spoon is absorbing all the heat, so it does not feel warm

Answer: (B)

Metal is an excellent heat conductor — heat from the hot soup travels quickly through the metal to the handle. Wood is a poor heat conductor (a good insulator) — heat moves through it very slowly. Both spoons are in equally hot soup; the difference is how fast each material lets the heat travel.

Question 2

A metal doorknob feels colder than a wooden door on a winter morning, so the metal should be at a lower temperature.

• T. True
• F. False

Answer: False

False. Both the doorknob and the door are at the same room temperature. Metal feels colder because it is a better conductor — it pulls heat away from your warm hand faster than wood does. The wood insulates, so heat leaves your hand slowly and your hand stays warm. The temperature difference is in how fast your hand loses heat, not in the actual temperature of the objects.

Question 3

Why are electrical wires made of copper but covered in plastic?

Model answer: Copper is an excellent conductor of electricity, so it carries the current efficiently. Plastic is an excellent insulator, so it prevents the electricity from escaping the wire and shocking people or causing short circuits.

This is a practical application of conductor and insulator properties. The copper core does the job of carrying electricity, and the plastic coating does the job of keeping that electricity safely contained. Each material is chosen for the property it contributes.