Which statement best describes conductors and insulators?

Which statement best describes conductors and insulators?

• A. Metals are insulators; rubber and plastics are conductors
• B. Water is always an insulator
• C. Metals are conductors; rubber and plastics are insulators
• D. Wood is a conductor; glass is an insulator

Answer: (C)

Materials differ in how easily charges can move through them. Metals have many free electrons that drift readily when an electric field is applied, so they conduct electricity well. Rubber and plastics, on the other hand, hold their electrons tightly and have high resistance, making them insulators that resist current. Water’s conductivity isn’t fixed: it depends on dissolved ions, so pure water is a poor conductor while common tap water can conduct due to impurities. Wood and glass are also insulators. So the statement that metals are conductors and rubber and plastics are insulators matches the typical behavior of these materials.

Materials differ in how easily charges can move through them. Metals have many free electrons that drift readily when an electric field is applied, so they conduct electricity well. Rubber and plastics, on the other hand, hold their electrons tightly and have high resistance, making them insulators that resist current. Water’s conductivity isn’t fixed: it depends on dissolved ions, so pure water is a poor conductor while common tap water can conduct due to impurities. Wood and glass are also insulators. So the statement that metals are conductors and rubber and plastics are insulators matches the typical behavior of these materials.