Electrical conductors are materials that allow electricity to flow easily, like silver, copper, and aluminum, while insulators resist electric current, such as rubber, glass, and plastic. In this article, we will dicuss 10 examples of each to understand their practical uses.
What Makes a Material an Electrical Conductor or Insulator?
At its core, whether a material conducts electricity or resists it depends on how easily electrons can move through it. Materials that allow electrons to flow freely are called electrical conductors, like copper, silver, and steel. Materials that resist electron flow are insulators, such as glass, rubber, and plastic.
While electrons can move, protons and neutrons remain fixed in atomic nuclei, so they don’t participate in conduction. This means conductivity is largely determined by the arrangement of electrons—especially the valence electrons in the outermost shell of atoms. Other factors, such as temperature, material size, and impurities, also significantly influence conductivity.
Conductors vs. Insulators: The Role of Valence Electrons
Think of valence electrons as planets orbiting a star. They’re held by their atoms but can be “nudged” out of position with relatively little energy. This makes them ideal carriers of electric current.
- Metals and plasmas are excellent conductors because their electrons are loosely bound and can move freely under an electric field.
- Organic molecules, on the other hand, are typically insulators. Their strong covalent bonds and additional hydrogen bonding create a stable structure that hinders electron movement, making electrical conduction difficult.
Some materials can behave differently under certain conditions:
- Doping: Adding small amounts of another element can turn an insulator into a conductor. For example, ceramics are normally insulators, but doped ceramics can become superconductors.
- Impurities: Pure water is a poor conductor, but adding salts creates free ions, improving conductivity.
Most materials, however, fall somewhere in between—they are neither perfect conductors nor perfect insulators.
Top 10 Electrical Conductors
The best conductors under ordinary conditions are metals with loosely bound electrons. The most efficient is silver, though its cost and susceptibility to tarnish limit practical use. Oxidation layers like rust, verdigris, or tarnish can significantly reduce conductivity. Other excellent conductors include:
- Silver
- Gold
- Copper
- Aluminum
- Mercury
- Steel
- Iron
- Seawater
- Graphite
- Brass/Bronze
Top 10 Electrical Insulators
Insulators prevent uncontrolled flow of electricity, making them crucial for safety and efficiency. They are commonly used to coat wires and separate conductive components. The strongest insulators include:
- Rubber
- Glass
- Pure water
- Oil
- Air
- Diamond
- Dry wood
- Dry cotton
- Plastic
- Asphalt
Additional insulators: Fiberglass, porcelain, ceramics, quartz, and dry paper.
Factors Affecting Electrical Conductivity
- Shape and Size of Material
- A thicker wire or material conducts better than a thinner one.
- Shorter lengths have less resistance than longer ones, similar to water flowing through a short versus long pipe.
- Temperature
- In most metals, conductivity decreases with rising temperature because increased atomic vibrations hinder electron flow.
- Some insulators, like glass, become better conductors at higher temperatures.
- Certain materials become superconductors at extremely low temperatures, allowing electrons to flow without resistance.
- Current-Induced Heating
- Electron flow generates heat due to resistance, which can affect conductivity. This is why wires warm up under heavy load.
Key Takeaways
- Metals and plasmas conduct electricity efficiently due to mobile valence electrons.
- Insulators, usually organic or covalently bonded substances, prevent free electron movement.
- Material properties and external factors like doping, impurities, size, and temperature play a crucial role in determining conductivity.
- Understanding these properties is essential for designing safe, efficient, and high-performance electrical systems.
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