Electrical principles - Properties
Insulators
Atoms with a valance shell that is completely full of electrons will not readily transfer them. Materials that are made up of atoms with these 'firmly bound' electrons are known as insulators.
Insulator material can be a solid, liquid or gas. Insulators are generally organic materials, but a number of inorganic materials are also good insulators. Examples of insulator materials used with electrical circuits include mica, glass, rubber and plastic.
Insulators have high resistance to electron flow.
Semiconductors
Semiconductors are insulators that conduct under certain conditions.
Some materials that are good insulators can, under different conditions, become good conductors. The conditions that can produce this change include high temperatures or a very high applied voltage.
Common semiconductor materials include germanium and silicon.
Semiconductors are used in electronic components such as diodes and transistors.