🔍 Key Concepts

• Difference between conductors, semiconductors, and insulators in basic electricity • How free electrons move (or don’t move) in metals versus non‑metals • Why vacuum and gases are often used around high‑voltage equipment

💭 Think About

• First, decide which listed materials are good conductors, which are semiconductors, and which are poor conductors of electricity • Ask yourself: in which pair do BOTH materials strongly resist the flow of electric current under normal conditions? • Think about practical examples: what kinds of materials are wrapped around wires or used between capacitor plates to prevent current flow?

✅ Before You Answer

• Eliminate any pair where either material is a metal, since metals are usually good conductors, not insulators • Eliminate any pair where the materials are commonly used as semiconductors in electronics (they conduct under certain conditions) • Focus on the pair where both materials are typically used to prevent current flow, especially in high‑voltage insulation or dielectric applications