Overview

Electricity – what is it?

Girl with hair standing on end

Why is this girl’s hair standing up?

Static electricity was the first kind of electricity that people discovered. We can all produce it by stroking a cat or rubbing a balloon¹.

Electricity can do useful work – if you use the correct device you can get heat, light, motion or other forms of energy from electricity. Survey a classroom or a room in your house and find the electrical appliances. You could make a list like the one below.

Devices that convert energy


Device	Power source	Converts from electricity to…
fan	power point	motion
torch	battery	light
headphones	battery (from phone or MP3 player)	sound

Hairdryer converting electricity to heat and motion of air

Hairdryers convert from electricity into...

What devices do you know that convert other forms of energy into electricity? You could make a list, using the table above as a starting point.

Extension: TechTopics² is a good source of ideas.

Where does our electricity come from?

Extension: All matter is made of tiny particles.

Graphic showing attraction and repulsion of positive and negative charges

'Like' charges repel, 'unlike' charges attract.

Many of these particles are charged, and the charge may be positive or negative. The particles that are easier to move are called electrons. They have a negative charge and are much too small for us to see. Negative charges repel each other. The hairs on the girl’s head have excess charges and those charges are repelling each other.

The Van de Graaff generator

Lightning

If the girl in the picture pushed her hair together, it would spring apart again. We spend energy pushing the hair together. While the hair is held together the energy is stored and we get it back as it springs apart.

The usual way for us to move electrons is through a metal wire. Most metals are good conductors of electricity – they allow the electrons to move through easily.

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Overview

Electricity – what is it?

Static versus current

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