Materials Conduct Electricity Differently
When it comes to electrical conductivity, not all materials are created equal. Some materials transfer electricity, heat, and sound easily, while others do not.
The electrical conductivity of a given material is determined by several factors: density, temperature, and the presence of free ions. Materials with free ions allow for smooth current flow because those ions and atoms are bound by attractive electrostatic forces.
Non-conductive materials are often referred to as “insulators.” Examples of insulators include rubber, wood, plastic, and glass. Highly conductive materials are usually called “conductors.” Common conductors include copper, graphite, and, surprisingly, the human body. A third category, “semiconductors,” refers to materials that offer moderate electrical conductivity. The most common semiconductors are silicon, germanium, and gallium arsenide.
Rubber
Rubber is a poor conductor of electricity. The chain polymer structure of rubber does not allow the free movement of electrons. Many electrical wire coatings are made from rubber for this exact reason. The rubber coating prevents the current from escaping the wiring and keeps the circuit intact. Additionally, electricians use thick rubber gloves to protect themselves from currents when working. As mentioned, the human body is an excellent conductor and will absorb electrical currents. Rubber gloves can protect electrical workers from dangerous, high-voltage currents on the job.
While pure rubber is a poor conductor, the right additives can alter the electrical conductivity of a rubber compound. Carbon or metallic additives, such as single-wall carbon nanotubes, can meaningfully increase the conductivity of a rubber material.
Metal
The atomic structure of metal allows for easy movement of free electrons between atoms. Because of this, most metals are excellent conductors of both heat and electricity. Silver is the most conductive metal on the planet, followed very closely by copper. Gold and aluminum also offer excellent conductivity. As with any material, each type of metal offers a blend of advantages and limitations. There are trade-offs to consider when choosing the best option for a given application.
Water
The electrical conductivity of water is nuanced. Truly pure water—distilled and deionized water—is an excellent insulator and does not conduct electricity. This may be surprising to anyone who has been warned to stay away from water during a lightning storm. But pure water is virtually nonexistent in the natural world. That’s because water is an excellent solvent: Chemicals, minerals, and other substances will dissolve easily into water. If a body of water contains a conductive element, such as salt, then that body of water will conduct electricity.
Copper
In addition to being an excellent conductor of electricity, copper has many attractive properties that make it an extremely popular choice for electrical wiring. Copper is flexible, strong, and resistant to rust. Copper often takes on a greenish patina, called copper oxide. Copper oxide offers an extra layer of protection against corrosion and does not affect the conductivity of the material.
