Define Conductor, Insulator and Semiconductor - QS Study
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We know, electric current is the flow of charges through a material. This electric current can move very easily through some substance. There are some mediums through which electricity cannot move at all. Solid materials are classified into three groups depending on their electricity conduction. For example: (1) conductor (2) insulator (3) semiconductor.

  • Insulator: The materials through which electric current cannot flow are called insulators. Therefore, the materials where electrons are not free to move about are the insulators. For example: Plastic, rubber, wood, glass etc. There are no free electrons inside insulating materials. Electrons do not flow easily through plastic type materials. As a result plastics are insulator for electricity. Due to this, the handles of screwdrivers and pliers used by electricians are covered with plastic type materials In addition, the copper wires which we use in our daily needs are covered with plastic.
  • Conductor: The materials through which electric current can flow very easily are called conductors. Electrons can flow freely within these materials. In metal wires the charges are carried by electrons. So, the metallic materials are good conductors of electricity. Copper, silver, aluminium etc. are good conductors. Due to this reason, metallic wires are used as electric connectors.
  • Semiconductor: The materials whose current conduction capacity lies between that of conductors and insulators in normal temperature are called semiconductors. For example- germanium, silicon etc. The current conduction capacity of semiconductor can be increased by adding suitable impurities.