Conductors / Insulators

Most materials fall into two groups:

• Conductors - allow electrons, and therefore a current, to flow through them.
• Insulators - do not conduct electricity

An insulator may act as a store of electricity known as static electricity.

There is a small third group called semi-conductors. These partially conduct electricity but have different properties to conductors. For example, as they are heated, their resistance goes down. Conductors' resistance increase as they get hotter.

Current is carried by electrons. Metals contain a "sea" of free electrons (negatively charged) which flow through the metal. This is what allows electric current to flow so well in all metals.

Some important facts that you really should know:

• Conventional current flows from Positive to Negative
• Electrical current flows from Negative to Positive
• So electrons flow opposite to the flow of conventional current

About the Author