Revise: Conductors, semiconductors and insulatorsClassifying materials
Solids can be categorised into conductors, semiconductors or insulators by their ability to conduct electricity. Electron band theory explains differences in conduction.
Materials can be placed into three groups according to their electrical resistanceThe opposition in an electrical component to the movement of electrical charge through it. Resistance is measured in ohms.:
conductorA material which allows charge to move easily through it. - have a very low resistance
semiconductorA material that will only allow charge to move easily through it under some conditions, for example when 'doped' with impurities. - pure semiconductors have a very high resistance
insulatorMaterial that does not allow charge or heat to pass through it easily. - have a very high resistance
This difference in conduction is explained by electron bands.
