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Conductivity: The Core Idea
- Electrical conductivity is the ability of a material to allow the flow of electric charge.
- In a material, current is produced only when mobile charge carriers move under an applied electric field.
- The charge carriers depend on the medium:
- Metals: mainly free or conduction electrons.
- Electrolytes: positive ions and negative ions.
- Semiconductors: electrons and holes.
- Ionised gases or plasma: electrons and positive or negative ions.
- Outer or valence electrons are farther from the nucleus and are generally less tightly bound than inner electrons.
- In metals, some valence electrons become delocalised. They are not attached to one particular atom and can move through the solid.
- An applied electric field gives these electrons a net drift motion, producing electric current.