Which material is a composite?
A. aluminum
B. gold
C. silicon
D. polycarbonate
D. polycarbonate
What happens to some metals when the kinetic energy of their particles is decreased?
A. They contract.
B. They melt.
C. They expand.
D. They conduct.
A. They contract.
Aluminum allows for the flow of electrons, while glass does not. Would an aluminum wire surrounded by glass be an effective design for a device that will need to carry an electric current?
A. No, it would not. Both aluminum and glass are insulators, so the device would not carry a current.
B. No, it would not. Both aluminum and glass are conductors, so the current would be exposed to outside elements.
C. Yes, it would. The glass would carry the current, while aluminum is an insulator.
D. Yes, it would. Aluminum is a conductor, and the glass would prevent electricity from transferring to a person holding the device.
B. No, it would not. Both aluminum and glass are insulators, so the device would not carry a current.
Which material would be a suitable insulator?
A. gold
B. silver
C. rubber
D. copper
C. rubber
An electrician is trying to decide which kind of material to use to wire a house.
carbon steel: conductivity = 1.43 × 10−7, resistance = 1 × 1010
copper: conductivity = 5.96 × 107, resistance = 1.68 × 10-8
gold: conductivity = 4.11 × 107, resistance = 2.44 × 10−8
iron: conductivity = 1 × 107, resistance = 1.0 × 10−7
Based on this information, which material should the electrician use?
A. iron
B. gold
C. copper
D. carbon steel
C. copper
Copper has the highest conductivity and the lowest resistance among the materials listed, making it the best choice for wiring a house.