Electricity and magnetism


Different ways electricity is produced or generatedDifferent ways electricity is produced or generated Electricity is a kind of energy stored inside atoms, the minute building blocks of which all things are made. Atoms themselves are made up of particles, including electrons, which have a negative electric charge, and protons, which have a positive electric charge. In normal atoms, there are the same number of electrons and protons, and so the charges cancel each other out. To make electricity, we must either make the atoms lose or gain electrons, or enable free electrons to move.

Producing static electricity by combingProducing static electricity by combing

Static electricity

In static electricity, the electrons do not move. It is produced when two objects rub against each other: the electrons rub off from the atoms of one material on to the other.

You can make static electricity by running a comb through your hair. The comb leaves a few of its electrons behind in the hair, so the comb now has a small positive charge. It can pick up small pieces of paper because it attracts the electrons in the paper’s atoms. If you comb your hair in a dark room then hold the comb close to your thumb, you will see a tiny spark. The release of electricity heats the air molecules (groups of atoms) between comb and thumb, producing a flash of light.

An electric charge heating air molecules is exactly what happens—but on a much grander scale—when lightning strikes during a thunderstorm. Lightning is static electricity that suddenly leaps between clouds and the ground, or from one cloud to another. Thunder is the noise of the air expanding rapidly in the intense heat.

Lightning, a dramatic release of static electricityLightning, a dramatic release of static electricity
Some electrons move freely in metals.Some electrons move freely in metals.

Current electricity

Electricity travels through space at the speed of light—about 300,000 kilometres per second. In a coaxial cable, where the conducting wire is surrounded by a polyethylene insulating layer, it travels at about 66% the speed of light.

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