10 Examples of Electrical Conductors and Insulators

Things That Don't Conduct Electricity and Things That Do

Illustration depicting examples of 5 electrical conductors and 5 electrical insulators

ThoughtCo.

What makes a material a conductor or an insulator? Simply put, electrical conductors are materials that conduct electricity and insulators are materials that do not. Whether a substance conducts electricity is determined by how easily electrons move through it.

Electrical conductivity is dependent on electron movement because protons and neutrons don't move—they are bound to other protons and neutrons in atomic nuclei.

Conductors Vs. Insulators

Valence electrons are like outer planets orbiting a star. They're attracted enough to their atoms to stay in position but it doesn't always take a lot of energy to knock them out of place—these electrons easily carry electric currents. Inorganic substances like metals and plasmas that readily lose and gain electrons top the list of conductors.

Organic molecules are mostly insulators because they're held together by covalent (shared electron) bonds and because hydrogen bonding helps stabilize many molecules. Most materials are neither good conductors nor good insulators but somewhere in the middle. These don't readily conduct but if enough energy is supplied, the electrons will move.

Some materials in pure form are insulators but will conduct if they are doped with small quantities of another element or if they contain impurities. For example, most ceramics are excellent insulators but if you dope them, you can create a superconductor. Pure water is an insulator, dirty water conducts weakly, and saltwater—with its free-floating ions—conducts well.

10 Electrical Conductors

The best electrical conductor, under conditions of ordinary temperature and pressure, is the metallic element silver. Silver is not always an ideal choice as a material, however, because it is expensive and susceptible to tarnishing, and the oxide layer known as tarnish is not conductive.

Similarly, rust, verdigris, and other oxide layers reduce conductivity even in the strongest conductors. The most effective electrical conductors are:

  1. Silver
  2. Gold
  3. Copper
  4. Aluminum
  5. Mercury
  6. Steel
  7. Iron
  8. Seawater
  9. Concrete
  10. Mercury

Other strong conductors include:

  • Platinum
  • Brass
  • Bronze
  • Graphite
  • Dirty water
  • Lemon juice

10 Electrical Insulators

Electric charges do not flow freely through insulators. This is an ideal quality in many cases—strong insulators are often used to coat or provide a barrier between conductors to keep electric currents under control. This can be seen in rubber-coated wires and cables. The most effective electrical insulators are:

  1. Rubber
  2. Glass
  3. Pure water
  4. Oil
  5. Air
  6. Diamond
  7. Dry wood
  8. Dry cotton
  9. Plastic
  10. Asphalt

Other strong insulators include:

  • Fiberglass
  • Dry paper
  • Porcelain
  • Ceramics
  • Quartz

Other Factors That Influence Conductivity

The shape and size of a material affect its conductivity. For example, a thick piece of matter will conduct better than a thin piece of the same size and length. If you have two pieces of a material of the same thickness but one is shorter than the other, the shorter one will conduct better because the shorter piece has less resistance, in much the same way that it's easier to force water through a short pipe than a long one.

Temperature also affects conductivity. As temperature increases, atoms and their electrons gain energy. Some insulators like glass are poor conductors when cool but good conductors when hot; most metals are better conductors when cool and less efficient conductors when hot. Some good conductors become superconductors at extremely low temperatures.

Sometimes conduction itself changes the temperature of a material. Electrons flow through conductors without damaging the atoms or causing wear. Moving electrons do experience resistance, though. Because of this, the flow of electrical currents can heat conductive materials.