Conductors and Insulators

The Properties of Conductors and Insulators.

In electrical and electronic cable circuits and components, CONDUCTORS are materials that allow electric current to flow through them and suitable materials include;

Most Metals

Some Gasses at low pressure

Solutions of Acids, Alkalis & Salts in water

Metals such as copper, aluminium, and some alloys (mixtures of two or more metals) containing copper, e.g. brass, phosphor bronze and manganin are widely used in electrical and electronics circuits. Electric wall sockets and switches use brass for their contacts and conductors.

Phosphor bronze, an alloy of copper and tin, with some phosphorous is springy in nature and useful for contacts, such as the "brushes" used to carry current between the stationary and rotating parts of the motor.

Manganin is another copper-based alloy used in the construction of wire wound resistors which are used in high power applications.

Aluminium is commonly as a conductor. Though not as good a conductor as copper, it is much lighter and useful for applications such as the large power distribution cables we see strung on electricity pylons. Copper cables would be too heavy for this job. Aluminium also has some properties, useful in the construction of transistors and diodes.

Silver is a better conductor than even copper, but since it is very expensive, it is only used in very small amounts. Some electrical contacts, which carry very small currents, may be silver-plated to improve their performance.

Materials that prevent the flow of electric current are called INSULATORS. Materials used in electronic circuits include;

• Plastics (e.g Polystyrene P.V.C & Polythene)
• Glass (including Fibre Glass)
• Ceramics
• Resins (e.g. epoxy resins)
• Paper (usually impregnated with resin etc.)
• Rubber (Natural or synthetic)
• Air

Both the terms "Insulator" and "Conductor" are relative. That is, they each have some properties of the other as well as their own. For example an insulator may pass very small currents, but not well enough to be called a conductor. An insulator can work well at low voltages, such as those found in battery operated equipment, but fail totally and pass large currents if connected to a much higher voltage.