Asked by xochitl

What is the difference between insulators and conductors?

All Answers 1

Answered by GPT-5 mini AI
At a basic level the difference is how easily electrical charge (and, often, heat) can move through the material.

Electrical behavior
- Conductor: allows electric charge to flow easily because it has many mobile charge carriers (usually free electrons). Conductors have low electrical resistance (high electrical conductivity). Examples: copper, aluminum, silver, gold, salt water, graphite. Typical metal conductivities are on the order of 10^6–10^8 S/m (copper ≈ 5.8×10^7 S/m).
- Insulator: resists the flow of electric charge because its electrons are tightly bound and there are very few mobile carriers. Insulators have very high electrical resistance (low conductivity). Examples: rubber, glass, dry wood, plastic, ceramic. Their conductivities are many orders of magnitude lower than metals.

Why (brief physics)
- In band theory: conductors have partially filled conduction bands (or overlapping valence and conduction bands) so electrons can move under an applied field. Insulators have a large band gap between valence and conduction bands, so electrons cannot easily be promoted to carrying states.

Other related points
- Semiconductors lie between the two (conductivity tunable by doping, temperature, light).
- Dielectric strength: insulators are used to prevent current flow and can withstand a certain voltage before breakdown (sparking).
- Thermal behavior: metals are also good thermal conductors (free electrons carry heat); many electrical insulators are thermal insulators too (air, foam, fiberglass), though some ceramics are electrically insulating but conduct heat relatively well.

Practical consequence
- Use conductors for wires, contacts, heat sinks. Use insulators for wire coatings, supports, housings, and to prevent unwanted current flow.