Which of the following is an insulator?

Which of the following is an insulator?

• A. Glass
• B. Copper
• C. Aluminum
• D. Gold

Answer: (A)

Electrical insulation relies on materials that do not allow charge to flow freely. Glass fits this because its atoms form a rigid network with very few free electrons that can move. In metals like copper, aluminum, and gold, electrons are largely free to move, so these materials conduct electricity and are good conductors. Glass, lacking free charge carriers, has a very high electrical resistance and therefore acts as an insulator. This is why glass is used to insulate electrical components and why metals are used for wires.

Electrical insulation relies on materials that do not allow charge to flow freely. Glass fits this because its atoms form a rigid network with very few free electrons that can move. In metals like copper, aluminum, and gold, electrons are largely free to move, so these materials conduct electricity and are good conductors. Glass, lacking free charge carriers, has a very high electrical resistance and therefore acts as an insulator. This is why glass is used to insulate electrical components and why metals are used for wires.