An electrical conductor is a material that allows electric current to flow through it easily. Conductors have low electrical resistance.
Why conductors conduct
In metals, the outer electrons of each atom are not tightly bound to individual atoms. These free electrons (also called delocalised electrons) can move through the metal lattice. When a potential difference is applied across the conductor, these free electrons drift in one direction, creating a current.
Common conductors
| Material | Notes |
|---|---|
| Copper | Used in most wiring because of its high conductivity and flexibility |
| Aluminium | Used in overhead power lines (lighter than copper) |
| Silver | The best conductor, but expensive |
| Gold | Used in electronic connectors (resists corrosion) |
| Steel | Used in structural applications where strength is needed |
Conductors vs insulators
The key difference is the number of free charge carriers. Conductors have many free electrons. Insulators have almost none. Semiconductors (such as silicon) fall between the two and their conductivity can be changed by adding impurities or changing temperature.
Temperature and conductivity
For most metals, resistance increases as temperature rises. The metal ions vibrate more, obstructing the flow of free electrons. This is the opposite of what happens in a thermistor (a semiconductor), where resistance decreases as temperature rises.
Need help understanding this?
A 0625 specialist can explain this concept using the student's own questions and show how it appears in exam papers.