Conductors and Insulators

Conductors

A conductor is an object or material that allows the flow of electrical current with considerably low resistance. Since the ability of a material to conduct electrical current depends on the number of free electrons, conductors are materials that have an abundance of free electrons. Metals are the best electrical conductors.

For the current to flow, one electron does not need to travel all the way from the source to the destination. Instead, the electron only needs to push a neighboring electron, which will, in turn, push its neighbor and so on until the final electron is pushed onto the destination, completing the current flow. It can be considered as a long chain of momentum transfer between moving electrons. This momentum transfer model makes metals an ideal choice for a conductor since metals characteristically possess delocalized electrons, which gives the electrons enough mobility to collide.

Delocalized electrons are free to move about in the molecular structure of that element as compared to localized ones, where the electrons are more tightly bound within the structure, limiting their mobility. Examples of good conductors are metals such as copper, aluminum, and silver and non-metals such as carbon. While metals are very good conductors of electricity, they still offer some resistance to the flow of electrons. This resistance to the flow of an electrical current gets converted to heat which is why conductors become hot. While the free mobility of electrons in metals makes for good conduction, increasing the temperature results in an acceleration in the electrons moving and colliding with each other, which reduces the ability of the metal to allow current to flow, effectively increasing its resistance.

Insulators

Insulators are materials that inhibit the flow of electrical current. They are the opposite of conductors. Their atoms have tightly bound electrons that cannot move smoothly throughout the material. Materials like plastic, rubber, and wood are considerably good insulators. In any electrical system, insulators play a very important role. Since it is important that electricity flow to a conductor through a specific path. Depending on the purpose, conductors cannot randomly connect with each other. In such a situation, insulators are placed between conductors to prevent the random flow of electricity.

The most common use of insulators, with plastic, cloth, or rubber as the material of choice, is around the electrical wires that supply electricity to and around your home. Each set of wires follows a specific path to drive a particular load (such as your lights and appliances). But there are many points, especially where they meet at the area for switches, where the wires may touch each other. Without insulation, the current would have flown randomly across the wires, making the set of circuits useless and dangerous.

Current can flow through the human body. The earth can be considered to be a point of very low voltage (reference zero voltage). If you touch a metal wire carrying a current, your body will act as the medium through which the current would flow, the return point being the earth. This action could be dangerous if the current is very high; hence, all conductors carrying electricity are covered with insulators.