Static Electricity

Understanding Static Electricity

  • Static electricity occurs when electric charges build up on the surface of a material.
  • It often happens when two insulating materials are rubbed together.
  • The charge that forms is called a static charge. It can stay for a long time and not move.
  • One of the materials loses electrons and becomes positively charged, while the other gains electrons and becomes negatively charged.
  • Like charges (two positives or two negatives) repel, while unlike charges (a positive and a negative) attract each other.

Effects of Static Electricity

  • When a charged object is brought near small bits of paper or hair, they can be attracted towards the object.
  • Static electricity can cause sparks. A spark is caused by a rapid movement of charges from a charged object to another object or into the air.
  • Sparks can be seen when the charge jumps across a gap – for example, when you touch a car door or metal object and get a small shock.

Applications of Static Electricity

  • Photocopiers and laser printers use static electricity to move ink directly onto the paper.
  • Static electricity is used in pollution control by using electrostatic precipitators which use static charge to attract dust and smoke particles from gases in industrial chimneys.
  • Static electricity can be put to use in paint spraying. The object to be painted is given a positive charge and the paint a negative charge, so each droplet of paint is attracted to the object, providing an even coat.

Dangers of Static Electricity

  • Static electricity can be a hazard in places where flammable substances are used or stored, as a spark could ignite the substances.
  • It can also be problematic in dry, windy weather conditions, leading to shocks and sparks which could cause fires.

Static Electricity and Earthing

  • To prevent potential hazards, a charged object can be connected to the ground using a conductor, a process called earthing.
  • When an object is earthed, the electrons will flow to or from the earth to remove the charge. This prevents any shocks or sparks that the accumulated static electricity might otherwise cause.