Conductors & Insulators (Edexcel IGCSE Physics)

Spec point — 2.22P · identify common materials which are electrical conductors or insulators, including metals and plastics (physics only)

Conductors, insulators & electrons

Conductors

• A conductor is a material that allows charge (usually electrons) to flow through it easily

• Examples of conductors are:

  • Silver
  • Copper
  • Aluminium
  • Steel

• Conductors tend to be metals

Different materials have different properties of conductivity

• On the atomic scale, conductors are made up of positively charged metal ions with their outermost electrons delocalised

  • This means the electrons are free to move

• Metals conduct electricity very well because:

  • Current is the rate of flow of electrons
  • So, the more easily electrons are able to flow, the better the conductor

The lattice structure of a conductor with positive metal ions and delocalised electrons

Insulators

• An insulator is a material that has no free charges, hence does not allow the flow of charge through them very easily

• Examples of insulators are:

  • Rubber
  • Plastic
  • Glass
  • Wood

• Some non-metals, such as wood, allow some charge to pass through them

• Although they are not very good at conducting, they do conduct a little in the form of static electricity

  • For example, two insulators can build up charge on their surfaces and if they touch this would allow that charge to be conducted away