Conductors and Insulators
A conductor conducts electricity. An insulator does not.
In a battery connected to a light bulb, the copper wire is a conductor covered by an insulator made of plastic. The wire allows electrons to flow, carrying the current.
The insulator prevents the current from flowing elsewhere, in case the wire touches another conductor.
Some electrons in a conductor can move. The electrons in an insulator cannot. One example is when you bring a charged glass rod to a metal ball.
If you hold one end of the glass rod with you hand, charges on the rod stay fixed at the other end. It does not flow to your hand, because glass is an insulator.
Electrons in the metal ball are attracted to the rod. They can move towards the rod, because metal is a conductor.
Metals are always conductors. Some non-metals are also conductors, like graphite and salt water.
Conductors:
- silver
- copper
- gold
- aluminum
- iron
- steel
- brass
- bronze
- mercury
- graphite
- salt water
- concrete
Non-metals are often insulators, but not always. Exceptions include graphite and salt water.
Insulators:
- glass
- rubber
- oil
- asphalt
- fiberglass
- porcelain
- ceramic
- quartz
- cotton
- paper
- wood
- plastic
- air
- diamond
- pure water