Static electricity

You can get an electrostatic shock if you are electrically 'charged' and you touch something that is earthed, or if you're earthed and you touch something that is charged.

For example, when you walk on a vinyl floor or a nylon carpet you 'charge up' because of friction. You can earth yourself, and so get an electrostatic shock by touching a metal door handle, water pipe, or even another person.

In this slideshow the man picks up electrons as he walks over the carpet:

A man faces a woman across a nylon carpet. The carpet is covered with electrons.

1. The carpet is covered with electrons

Problems with static

Here are some examples of problems associated with static:

  • it is a nuisance when dust and dirt are attracted to insulators such as TV screens and computer monitors.
  • it is a nuisance when clothes made from synthetic materials cling to each other and to the body, especially just after they've been in a tumble dryer

Anti-static sprays, liquids and cloths prevent the build-up of charge by allowing it to conduct away.

Dangers of static

Static electricity can build up in clouds. This can cause a huge spark to form between the ground and the cloud. This causes lightning – a flow of charge through the atmosphere.

Here are some examples of dangers associated with static electricity:

  • It is dangerous when there are flammable gases or a high concentration of oxygen. A spark could ignite the gases and cause an explosion.
  • It is dangerous when you touch something with a large electric charge on it. The charge will flow through your body causing an electric shock. This could cause burns or even stop your heart. A person could die from an electric shock.

Refuelling aircrafts and tankers also poses a particular danger. If the fuel passing along the hose to the vehicle was allowed to build up a static charge, a resulting spark might ignite the fuel. The hoses are earthed to stop this occurring.