Here's a scary thought: No TV, no films, no video games, no recorded music, no electric lighting, no electrical machinery, no medical technology, no computers, no phones, no internet, no PhysicsFox.org.

Shockingly, none of these could have existed before around 150 years ago, when electricity was first understood.

Electricity is the flow of electrons.

Electrons are tiny particles which have a negative charge. Over the next couple of pages, we'll find out what charge is, and where electrons come from.

For electricity to be useful, it needs to flow in a path called a circuit. The electrons flow because they're being pushed around by a force called the electric force, which is one of the fundamental forces. Once we know more about the electric force, we'll spend the majority of the chapter learning about circuits.

Electrons can flow through materials called conductors, but cannot flow not through insulators.

Examples of each of these include:

Examples of conductors:

• Metals (e.g. copper, iron, gold). Most electrical wires are made from copper, because it is cheap, conducts electricity well, and can be drawn into thin wires.


• Graphite. This is what's left on paper when you draw with a pencil.


• Water. This is why you shouldn't go from an outdoor swim during a thunderstorm!


• The human body. We are mostly water, after all. (Although people are quite bad conductors compared to metals.)


• The Earth. (Also a relatively bad conductor compared to metal)

Examples of insulators:

• Wood.


• Plastics. This is why you find rubber tubing around electrical wires.


• Fabric. (This is because fabrics are made from plants and plastics.)


• Ceramics


• Glass


• Air. (If air were a conductor, you would be electrocuted anytime you went near a pylon.)

Interestingly, materials that are good conductors of electricity are also good conductors of heat.